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Increased Curie Temperature Induced by Orbital Ordering in La0.67Sr0.33MnO3/BaTiO3 Superlattices
Nanoscale Research Letters volume 13, Article number: 24 (2018)
Recent theoretical studies indicated that the Curie temperature of perovskite manganite thin films can be increased by more than an order of magnitude by applying appropriate interfacial strain to control orbital ordering. In this work, we demonstrate that the regular intercalation of BaTiO3 layers between La0.67Sr0.33MnO3 layers effectively enhances ferromagnetic order and increases the Curie temperature of La0.67Sr0.33MnO3/BaTiO3 superlattices. The preferential orbital occupancy of eg(x2–y2) in La0.67Sr0.33MnO3 layers induced by the tensile strain of BaTiO3 layers is identified by X-ray linear dichroism measurements. Our results reveal that controlling orbital ordering can effectively improve the Curie temperature of La0.67Sr0.33MnO3 films and that in-plane orbital occupancy is beneficial to the double exchange ferromagnetic coupling of thin-film samples. These findings create new opportunities for the design and control of magnetism in artificial structures and pave the way to a variety of novel magnetoelectronic applications that operate far above room temperature.
A common observation in perovskite manganite films is that the Curie temperature (TC) decreases with the reduction of film thickness, which limits their potential for spintronic devices such as field-effect transistors, magnetic tunnel junctions, spin valves, and nonvolatile magnetic memory [1,2,3,4,5]. This is the so-called “dead layer,” defined as the thinnest layer for which ferromagnetic behavior is observed [6,7,8]. This dead layer phenomenon may be related to electronic and/or chemical phase separation [9, 10], to growth characteristics and microstructure [11, 12], or to manganese eg orbital reconstruction [13, 14]. Recently, many efforts have been made to increase the TC of ultrathin perovskite manganite films by superlattice interface control and precise strain tuning [15,16,17,18]. Among the perovskite manganites, La0.67Sr0.33MnO3 (LSMO) films have drawn increasing interest due to their colossal magnetoresistance effect, high TC, and half metallicity [19,20,21,22,23]. Also LSMO-based heterostructures have been investigated because of the interfacial couplings and intermixing of atoms etc. [24,25,26,27,28]. M. Ziese et al. reported ferromagnetic order of ultrathin LSMO layers in LSMO/SrRuO3 superlattices stabilized down to layer thicknesses of at least two unit cells (u.c.) that exhibits a TC above room temperature . First principle calculations indicate that the TC of LSMO films can be increased by more than an order of magnitude by controlling orbital ordering using the regular intercalation of adequate layers in LSMO/BaTiO3(BTO) superlattices. In such a configuration, the LSMO layers with occupied eg(x2–y2) orbitals are associated with a strong in-plane double exchange, resulting in a high TC . This phenomenon has been observed in temperature-dependent magnetization data .
In this work, we synthesized LSMO/BTO superlattices using pulsed laser deposition (PLD) and reveal the relationship between the origin of high TC and manganese eg orbital occupancy through the use of X-ray linear dichroism (XLD) measurements. We show that the regular intercalation of BTO layers between LSMO layers can effectively enhance ferromagnetic order and increases the TC of ultrathin LSMO films due to the orbital occupation of eg(x2–y2) in Mn3+ ions. Notably, the origin of the TC increase is different from the one suggested theoretically by A. Sadoc et al., who showed that only the central LSMO layers contribute to high TC and that the interfacial layers adjacent to the BTO layers are associated with a weak in-plane double exchange due to eg(3z2–r2) orbital occupation . We find that the preferential orbital occupancy of eg(x2–y2) in both of the central and the interfacial LSMO layers is induced by BTO layer strain, and gives rise to the in-plane double exchange coupling in LSMO/BTO superlattices, resulting in high TC. Our findings provide a method to design and control magnetism in artificial structures and have potential for spintronic device applications—including spin-valve devices or nonvolatile magnetic memory working at temperatures far above room temperature.
(001)-oriented [(LSMO)3/(BTO)3] n superlattice (denoted as SL-n, where 3 is the number of unit cells, n = 3, 4, 10 is the number of cycles) samples were synthesized on (001) SrTiO3 substrates using PLD. A stoichiometric polycrystalline target was used in a 100-mTorr oxygen environment at a substrate temperature of 725 and 780 °C for LSMO and BTO, respectively. A KrF excimer laser (λ = 248 nm) with a 2 Hz repetition rate was employed. Energy of 350 and 300 mJ was focused on the targets to obtain the LSMO and BTO layers, respectively. After the growth, the samples were annealed in a 300-Torr oxygen atmosphere in situ for 1 h to improve their quality and reduce their inherent oxygen deficit and then cooled to room temperature. As a reference, two LSMO films with 3 and 40 u.c. thickness (denoted as LSMO(3) and LSMO(40), respectively) were also prepared using PLD under the same conditions for comparison with the SL-n superlattices. To grow films epitaxially with atomic precision, we prepared an atomically flat, single-terminated SrTiO3 surface by etching in an NH4F-buffered HF solution (BHF) and subsequently annealing in an oxygen atmosphere at a temperature of 960 °C. The surface topography of a BHF-treated, bare (001) SrTiO3 substrate was characterized by atomic force microscopy (AFM) analysis, as shown in Fig. 1d. The surface is very smooth, and there are clear steps separating the terraces.
The growth process for each film was monitored in situ using real-time reflection high-energy electron diffraction (RHEED) analysis, providing precise control of the thickness at the unit cell scale and an accurate characterization of the growth dynamics. The crystal structures and surface morphologies were investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). To confirm the strain in the samples, Raman spectra were also recorded using a microscopic confocal Raman spectrometer (RM2000, Renishaw, England) excited with a 514.5 nm Ar+ ion laser. The magnetic properties and TC of the samples were measured with a superconducting quantum interference device (SQUID) magnetometer with in-plane applied magnetic field. The magnetization was calculated after a linear background subtraction of the SrTiO3 substrate diamagnetic contribution. The transport properties were determined in the Van der Pauw four-point probe configuration using a Quantum Design Physical Properties Measurement System (PPMS) over temperatures ranging from 20 to 365 K. X-ray absorption spectroscopy (XAS) and XLD measurements were made at Beamline BL08U1A of the Shanghai Synchrotron Radiation Facility and U19 of National Synchrotron Radiation Laboratory in the total electron yield (TEY) mode at room temperature.
Results and Discussion
Figure 1a shows the RHEED oscillations recorded during the growth of the SL-3 sample on a TiO2-terminated (001) SrTiO3 substrate. The LSMO and BTO film thicknesses were controlled by counting the RHEED intensity oscillations. For optimized conditions, RHEED oscillations remain visible throughout the superlattice deposition process, indicating a layer-by-layer growth. The inset of Fig. 1d shows the clear streaky RHEED diffraction pattern after the growth of the SL-3 sample. Typical XRD patterns shown in Fig. 1b reveal high-quality growth in the (001) orientation for all three superlattices. As expected, the LSMO peaks shift slightly to a higher angle while the BTO peaks shift to a lower angle (compared to the bulk value), which reflects the strain state of the interfaces between the LSMO layers and the BTO layers (i.e., in-place cell parameter elongation for LSMO and reduction for BTO). This desired strain can be maintained over the whole film thickness due to the repeating intercalation of LSMO and BTO layers. Raman spectra measured at 300 K for the SL-10 and LSMO(40) samples are shown in Fig. 1c. Compared to LSMO(40) sample, a slight low-frequency shift of bands at 252 cm− 1 was observed in SL-10 sample, indicating the LSMO layers in SL-10 sample with a tensile strain induced by BTO layers [31,32,33]. In addition, the high quality of the superlattices was confirmed by TEM. Figure 2a is the cross-sectional high-resolution TEM (HRTEM) of the SL-3 sample on a (001)-oriented SrTiO3 substrate, endorsing high-quality epitaxial growth of LSMO/BTO superlattice. The inset of Fig. 2a is the corresponding fast Fourier transform (FFT), suggesting that the film is indeed in single phase. Figure 2b shows the enlarged image of Fig. 2a. The image shows atomically sharp interfaces between the LSMO and BTO layers highlighted by red arrows. In the superlattices, there is no obvious interdiffusion at the interfaces, and the LSMO and BTO layers are fully strained to the SrTiO3 substrates. This observation was consistent with the XRD results.
Next, we present a description of the magnetic properties of the SL-n samples. The temperature-dependent magnetization for SL-n films with n = 3, 4, 10, as well as the LSMO(3) sample, are shown in Fig. 3a. Here, the measurement is carried out over a temperature range from 5 to 350 K with a magnetic field (3000 Oe) applied parallel to the surface of the SrTiO3 substrates. Note that the TC of the superlattices is significantly improved compared to the LSMO(3) film , of which TC is around 45 K (see the inset in Fig. 3a). For the SL-10 sample, the TC increases above 265 K compared to the LSMO(3) film and reaches a maximum value of TC~310 K. Figure 3b shows corresponding magnetic hysteresis loops for the four samples measured at 5 K, showing obvious ferromagnetic signal with a saturation magnetization (Ms) of ~ 1.5 μB/Mn—except for the LSMO(3) film. Here, the ferromagnetism of the LSMO layers in the SL-n samples comes from the total LSMO triple layers, which is different from those reported by A. Sadoc et al., who showed that the ferromagnetic exchange is just related to the central LSMO layers and is independent of the interfacial LSMO layers adjacent to BTO layers using first principle calculations . Given that ferromagnetism is only derived from the central LSMO layers, the Ms value of our SL-n films calculated from the original measurement data will become ~ 4.5 μB/Mn, which will exceed the theoretical low temperature value of the LSMO (~ 3.67 μB/Mn) . Note that the Ms per spin is much less than of bulk LSMO, suggesting either a fraction of nonmagnetic spins, a ferrimagnetic spin arrangement, or strong spin-canting [18, 35]. More work will be needed to quantify decreased Ms in this LSMO/BTO system. Also, the magnetic anisotropy of the SL-n samples with n = 3, 4, 10 were studied. The magnetic hysteresis loops for the magnetic field applied in-plane and out-of-plane measured at 5 K (not shown here) display that the easy magnetization axis for the three samples is parallel to the film plane direction, which is related to the orbital occupancy in LSMO layers, as discussed below.
We now focus on the correlation between increased TC and electron orbital occupancy in the LSMO/BTO superlattices. It is known that the Mn3+ ions are Jahn-Teller active, and a slightly distorted orthorhombic structure can stabilize one of the eg orbitals. Supposing the eg(3z2–r2) is occupied, an interlayer double exchange interaction between the Mn3+ and Mn4+ ions will take place primarily along the c direction for (001)-oriented LSMO material. When eg(x2–y2) is occupied, the intralayer double exchange will become very strong and the interlayer double exchange will decline in strength. In ultrathin films, in-plane interactions dominate the magnetic exchange and TC. Thus, control of the orbital ordering is important for obtaining high-temperature ferromagnetism. That is to say, a high-occupancy probability of the eg(x2–y2) orbital can result in a high TC for (001)-oriented LSMO films.
In our LSMO/BTO samples, the lattice parameter of the BTO (a = 0.397–0.403 nm from a tetragonal to rhombohedral phase) is larger than that of LSMO (a = 0.387 nm), resulting in a ~ 4% lattice mismatch [36,37,38]. Thus, the LSMO layers in our superlattices are in a high-tensile strain state (c < a), causing occupancy in the eg(x2–y2) orbital . We now discuss the manganese eg orbital occupancy in relation to XLD measurements, which is an extremely sensitive probe for the electronic structure and the d orbital (eg) electron occupancy (schematic diagram shown in Fig. 4d), which has proven in referential occupancy at interfaces . The XAS spectra were measured at the Mn L2,3-edges for the photon polarization (E) parallel to the sample plane (E//) and perpendicular to it (E⊥). The XLD is calculated as the XAS intensity difference between the E// and E⊥ components to determine the occupancy of the Mn3+ eg orbitals. In (001)-oriented LSMO films, the out-of-plane direction corresponds to , and the in-plane direction was obtained with E//, as shown in Fig. 4d. The area under the XLD curve at the L2-edge peak (ΔXLD) represents the difference between the relative occupancies of the eg(x2 − y2/3z2 − r2) orbitals. A positive/negative ΔXLD (on average) is ascribed attributed to a preferential occupancy of the eg(3z2 − r2)/(x2 − y2) orbitals for (001) LSMO films. Figure 4a, b shows the XLD spectra, as well as the in-plane and out-of-plane XAS spectra, of SL-3 and SL-10 samples. The ΔXLD area at the L2-edge peak is negative, implying a preferential occupancy of the eg(x2–y2) orbital (see Fig. 4e), which is consistent with the results reported by D. Pesquera et al. . Consequently, in our LSMO/BTO superlattices, the interfacial tensile strain is originated from the lattice mismatch between the BTO and LSMO layers. It induces in-plane orbital ordering of the eg(x2–y2) orbital occupancy in the LSMO layers, achieving high TC. This negative value of the ΔXLD area is also evidence that the Mn3+ ions in the LSMO triple layers have the same orbital occupancy, which contributes to high-temperature ferromagnetism. Also, the absolute value of ΔXLD for the SL-10 sample is significantly larger than that of the SL-3 sample, which corresponds to the increased TC seen in Fig. 3a.
Figure 4c shows temperature-dependent resistivity in the temperature range from 20 to 365 K for (001)-oriented SL-n superlattices with n = 3 and 10, respectively. The two samples exhibit a metal-to-insulator transition temperature (TMI). The TMI values of 178 and 310 K for samples SL-3 and SL-10, respectively, correspond to the TC shown in Fig. 3a. This supports the scenario for a transition at TC from a paramagnetic insulating phase to a ferromagnetic metallic phase. Thus, the high-temperature ferromagnetism originates from in-plane double exchange interactions between the Mn3+ and Mn4+ ions as shown in Fig. 4f [40, 41]. In-plane overlap between (partly filled) Mn eg(x2–y2) with O 2p x and O 2p y creates stronger ferromagnetic coupling than that between (more empty) Mn eg(3z2–r2).
In summary, LSMO/BTO superlattices were prepared using PLD and the relationship between high TC and manganese eg orbital occupancy was revealed combined with XLD spectra. We showed that the regular intercalation of BTO layers between LSMO layers effectively enhances ferromagnetic order and increases the TC of LSMO/BTO superlattices. The preferential orbital occupancy of eg(x2–y2) in LSMO layers induced by tensile strain of BTO layers is beneficial to the in-plane double exchange ferromagnetic coupling between Mn3+ and Mn4+ ions, resulting in a large TC. Our findings create new opportunities for the design and control of magnetism in artificial structures and offer considerable potential for applications in novel magnetoelectronic applications, including nonvolatile magnetic memory working far above room temperature.
Atomic force microscopy
NH4F-buffered HF solution
Fast Fourier transform
- M s :
Pulsed laser deposition
Physical properties measurement system
Real-time reflection high-energy electron diffraction
Superconducting quantum interference device
- T C :
Transmission electron microscopy
Total electron yield
- T MI :
Metal-to-insulator transition temperature
X-ray absorption spectroscopy
X-ray linear dichroism
Thiel S, Hammerl G, Schmehl A, Schneider CW, Mannhart J (2006) Tunable quasi-two-dimensional electron gases in oxide heterostructures. Science 313:1942–1945
Hueso LE, Pruneda JM, Ferrari V, Burnell G, Valdes-Herrera JP, Simons BD, Littlewood PB, Artacho E, Fert A, Mathur ND (2007) Transformation of spin information into large electrical signals using carbon nanotubes. Nature 445:410–413
Qin Q, He S, Song W, Yang P, Wu Q, Feng YP, Chen J (2017) Ultra-low magnetic damping of perovskite La0.7Sr0.3MnO3 thin films. Appl Phys Lett 110:112401
Liang L, Li L, Wu H, Zhu X (2014) Research progress on electronic phase separation in low-dimensional perovskite manganite nanostructures. Nanoscale Res Lett 9:325
Zheng D, Jin C, Li P, Wang L, Feng L, Mi W, Bai H (2016) Orbital reconstruction enhanced exchange bias in La0.6Sr0.4MnO3/orthorhombic YMnO3 heterostructures. Sci Rep 6:24568
Huijben M, Martin LW, Chu YH, Holcomb MB, Yu P, Rijnders G, Blank DHA, Ramesh R (2008) Critical thickness and orbital ordering in ultrathin La0.7Sr0.3MnO3 films. Phys Rev B 78:094413
Yamada H, Ogawa Y, Sato YH, Kawasaki M, Akoh H, Tokura Y (2004) Engineered interface of magnetic oxides. Science 305:646–648
Peng R, Xu HC, Xia M, Zhao JF, Xie X, Xu DF, Xie BP, Feng DL (2014) Tuning the dead-layer behavior of La0.67Sr0.33MnO3/SrTiO3 via interfacial engineering. Appl Phys Lett 104:081606
Infante IC, Sánchez F, Fontcuberta J, Wojcik M, Jedryka E, Estradé S, Peiró F, Arbiol J, Laukhin V, Espinós JP (2007) Elastic and orbital effects on thickness-dependent properties of manganite thin films. Phys Rev B 76:224415
Mundy JA, Hikita Y, Hidaka T, Yajima T, Higuchi T, Hwang HY, Muller DA, Kourkoutis LF (2014) Visualizing the interfacial evolution from charge compensation to metallic screening across the manganite metal–insulator transition. Nat Commun 5:3464
Xie C, Budnick JI, Wells BO, Woicik JC (2007) Separation of the strain and finite size effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films. Appl Phys Lett 91:172509
Ziese M, Semmelhack HC, Han KH (2003) Strain-induced orbital ordering in thin La0.7Ca0.3MnO3 films on SrTiO3. Phys Rev B 68:134444
Tebano A, Aruta C, Sanna S, Medaglia PG, Balestrino G, Sidorenko AA, De Renzi R, Ghiringhelli G, Braicovich L, Bisogni V, Brookes NB (2008) Evidence of orbital reconstruction at interfaces in ultrathin La0.67Sr0.33MnO3 films. Phys Rev Lett 100:137401
Tebano A, Orsini A, Medaglia PG, Castro DD, Balestrino G, Freelon B, Bostwick A, Chang YJ, Gaines G, Rotenberg E, Saini NL (2010) Preferential occupation of interface bands in La2/3Sr1/3MnO3 films as seen via angle-resolved photoemission. Phys Rev B 82:214407
Ma JX, Liu XF, Lin T, Gao GY, Zhang JP, Wu WB, Li XG, Shi J (2009) Interface ferromagnetism in (110)-oriented La0.7Sr0.3MnO3/SrTiO3 ultrathin superlattices. Phys Rev B 79:174424
Choi E-M, Kleibeuker JE, Fix T, Xiong J, Kinane CJ, Arena D, Langridge S, Chen A, Bi Z, Lee JH, Wang H, Jia Q, Blamire MG, MacManus-Driscoll JL (2016) Interface-coupled BiFeO3/BiMnO3 superlattices with magnetic transition temperature up to 410 K. Adv Mater Interfaces 3:1500597
Choi EM, Kleibeuker JE, JL MM-D (2017) Strain-tuned enhancement of ferromagnetic TC to 176 K in Sm-doped BiMnO3 thin films and determination of magnetic phase diagram. Sci Rep 7:43799
Boschker H, Kautz J, Houwman EP, Siemons W, Blank DHA, Huijben M, Koster G, Vailionis A, Rijnders G (2012) High-temperature magnetic insulating phase in ultrathin La0.67Sr0.33MnO3 films. Phys Rev Lett 109:157207
Bowen M, Bibes M, Barthelemy A, Contour JP, Anane A, Lemaitre Y, Fert A (2003) Nearly total spin polarization in La2/3Sr1/3MnO3 from tunneling experiments. Appl Phys Lett 82:233–235
Zhou G, Guan X, Bai Y, Quan Z, Jiang F, Xu X (2017) Interfacial spin glass state and exchange bias in the epitaxial La0.7Sr0.3MnO3/LaNiO3 bilayer. Nanoscale Res Lett 12:330
Park JH, Vescovo E, Kim HJ, Kwon C, Ramesh R, Venkatesan T (1998) Direct evidence for a half-metallic ferromagnet. Nature 392:794–796
Quan Z, Wu B, Zhang F, Zhou G, Zang J, Xu X (2017) Room temperature insulating ferromagnetism induced by charge transfer in ultrathin (110) La0.7Sr0.3MnO3 films. Appl Phys Lett 110:072405
Štrbík V, Reiffers M, Dobročka E, Šoltýs J, Španková M, Chromik Š (2014) Epitaxial LSMO thin films with correlation of electrical and magnetic properties above 400K. Appl Surf Sci 312:212–215
Yin L, Zhang Q, Li D, Mi WB, Wang X (2016) Electric field modulation on special interfacial magnetic states in tetragonal La2/3Sr1/3MnO3/BiFeO3 heterostructures. J Phys Chem C 120:15342–15348
Werner R, Petrov AY, Mno LA, Kleiner R, Koelle D, Davidson BA (2011) Improved tunneling magnetoresistance at low temperature in manganite junctions grown by molecular beam epitaxy. Appl Phys Lett 98:162505
Feng N, Mi WB, Wang X, Cheng Y, Schwingenschlögl U (2015) Superior properties of energetically stable La2/3Sr1/3MnO3/tetragonal BiFeO3 multiferroic superlattices. ACS Appl Mater Interfaces 7:10612–10616
Matou T, Takeshima K, Anh LD, Seki M, Tabata H, Tanaka M, Ohya S (2017) Reduction of the magnetic dead layer and observation of tunneling magnetoresistance in La0.67Sr0.33MnO3-based heterostructures with a LaMnO3 layer. Appl Phys Lett 110:212406
Yin L, Zhang Q, Mi WB, Wang X (2016) Strain-controlled interfacial magnetization and orbital splitting in La2/3Sr1/3MnO3/tetragonal BiFeO3 heterostructures. J Appl Phys 120:165303
Ziese M, Bern F, Pippel E, Hesse D, Vrejoiu I (2012) Stabilization of ferromagnetic order in La0.7Sr0.3MnO3–SrRuO3 superlattices. Nano Lett 12:4276–4281
Sadoc A, Mercey B, Simon C, Grebille D, Prellier W, Lepetit MB (2010) Large increase of the Curie temperature by orbital ordering control. Phys Rev Lett 104:046804
Kreisel J, Lucazeau G, Dubourdieu C, Rosina M, Weiss F (2002) Raman scattering study of La0.7Sr0.3MnO3/SrTiO3 multilayers. J Phys Condens Matter 14:5201
Bormann D, Desfeux R, Degave F, Khelifa B, Hamet JF, Wolfman J (1999) Lattice mismatch effects between the substrate and GMR La0.7Sr0.3MnO3 thin films studied by scanning probe microscopy and Raman spectroscopy. Phys Stat Sol (b) 215:691–695
Martincarron L, Andres AD, Martinezlope MJ, Casais MT, Alonso JA (2002) Raman phonons as a probe of disorder, fluctuations and local structure in doped and undoped orthorhombic and rhombohedral manganites. Phys Rev B 66:174303
Böttcher D, Henk J (2013) Magnetic properties of strained La2/3Sr1/3MnO3 perovskites from first principles. J Phys Condens Matter 25:136005
Mizumaki M, Chen WT, Saito T, Yamada I, Attfield JP, Shimakawa Y (2011) Direct observation of the ferrimagnetic coupling of A-site Cu and B-site Fe spins in charge-disproportionated CaCu3Fe4O12. Phys Rev B 84:094418
Murugavel P, Prellier W (2006) The magnetotransport properties of La0.7Sr0.3MnO3∕BaTiO3 superlattices grown by pulsed laser deposition technique. J Appl Phys 100:023520
Chang K-S, Aronova MA, Lin C-L, Murakami M, Yu M-H, Hattrick-Simpers J, Famodu OO, Lee SY, Ramesh R, Wuttig M, Takeuchi I, Gao C, Bendersky LA (2004) Exploration of artificial multiferroic thin-film heterostructures using composition spreads. Appl Phys Lett 84:30913093
Xiao CJ, Jin CQ, Wang XH (2008) Crystal structure of dense nanocrystalline BaTiO3 ceramics. Mater Chem Phys 111:209–212
Pesquera D, Herranz G, Barla A, Pellegrin E, Bondino F, Magnano E, Sanchez F, Fontcuberta J (2012) Surface symmetry-breaking and strain effects on orbital occupancy in transition metal perovskite epitaxial films. Nat Commun 3:1189
Zener C (1951) Interaction between the d-shells in the transition metals. II. Ferromagnetic compounds of manganese with perovskite structure. Phys Rev 82:403
de Gennes PG (1960) Effects of double exchange in magnetic crystals. Phys Rev 118:141
The work is financially supported by the NSFC (nos. 51571136, 61434002, and 61306109), the Ministry of Education of China (no. IRT 1156), and Shanxi Scholarship Council of China (no. 2015-069). The authors also acknowledge Beamline BL08U1A (Shanghai Synchrotron Radiation Facility, China) and U19 (National Synchrotron Radiation Laboratory, China) stations for XAS measurements.
The authors declare that they have no competing interests.
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Zhang, F., Wu, B., Zhou, G. et al. Increased Curie Temperature Induced by Orbital Ordering in La0.67Sr0.33MnO3/BaTiO3 Superlattices. Nanoscale Res Lett 13, 24 (2018). https://doi.org/10.1186/s11671-018-2441-5
- La0.67Sr0.33MnO3/BaTiO3 superlattices
- High Curie temperature
- Orbital ordering
- Tensile strain