Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

Rajapitamahuni, Anil; Zhang, L.; Koten, Mark A.; Singh, V. R.; Burton, John; Tsymbal, Evgeny Y.; Shield, Jeffrey E.; Hong, Xia

doi:10.1103/physrevlett.116.187201

Cited by 42 publications

(26 citation statements)

References 37 publications

(57 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The 5 uc film, on the other hand, exhibits considerably higher T min (≈70 K) and enhanced resistivity ρ xx (Figure a,b). Such suppressed metallicity, along with the lower magnetic ordering temperature, in the ultrathin limit has been widely observed in epitaxial correlated oxide thin films, while the driving mechanism can be associated with the thickness‐driven dimensionality crossover, energy gap formation due to enhanced correlation, and/or variation in the oxygen octahedral distortion at the surface/interface . In all films, the longitudinal resistivity exhibits very weak T ‐dependence, with the residue resistance ratio ρ xx ( T min )/ρ xx (300 K) ranging from 0.67 to 0.77, which is the signature behavior of a multiband conductor with both electron and hole bands close to the Fermi level ( E F ) .…”

mentioning

confidence: 86%

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo₂O₄ Thin Films

et al. 2018

View full text Add to dashboard Cite

While previous studies of NCO have mainly centered on nanostructured and mesoporous materials, [6][7][8]15,16] it is of high research interest to examine the system in the epitaxial thin film form, especially for developing spintronic applications such as spinel-based magnetic tunnel junctions (MTJs). [17,18] To date, reports on high-quality NCO thin films have been scarce and mostly focused on the disorder-driven metal-insulator transition, [3,5,11,14,19,20] while the intrinsic magnetotransport properties in the metallic phase remain uncharted.In this work, we report the magnetotransport anomalies observed in 5-30 unit cell (uc) thick high-quality epitaxial NCO thin films. Below the magnetic ordering temperature, NCO exhibits strong out-of-plane magnetic anisotropy, linear magnetoresistance (MR), and robust anomalous Hall effect (AHE) that persist above room temperature. The longitudinal resistance exhibits a weak temperature dependence that cannot be directly correlated with the magnetic state of the system. The anomalous Hall conductivity (σ xy ) shows an unusual nonmonotonic temperature dependence, which changes sign in the thinner films. The relation between σ xy and the longitudinal conductivity (σ xx ) at the intermediate temperature range points to the dirty metal behavior in conjunction with the contribution from band intrinsic Berry phase effect, while the low-temperature characteristic can be attributed to disorderenhanced electron correlation. Our work provides critical information on how to manipulate the competing energy scales in this system to achieve tailored functionalities for spintronic applications.We deposited high-quality 5-30 uc epitaxial NCO films on (001)-oriented MgAl 2 O 4 (MAO) substrates. The bulk cubic lattice constant of NCO is 8.128 Å, subjecting to a 0.55% compressive strain when grown on MAO (a = 8.083 Å). X-ray diffraction (XRD) measurements show (001) growth with no impurity phases (Figure 1b). The calculated c-axis lattice constant is 8.196 Å, comparable with the reported values for strained films. [11,19] Figure 1c,d shows the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images of a 17 uc NCO film, which reveal a homogeneous inverse spinel structure with high crystallinity. Atomic force microscopy (AFM) measurements show smooth surface morphology in these samples (Figure 1e), with typical root mean square roughness of 2-3 Å.The inverse spinel ferrimagnetic NiCo 2 O 4 presents a unique model system for studying the competing effects of crystalline fields, magnetic exchange, and various types of chemical and lattice disorder on the electronic and magnetic states. Here, magnetotransport anomalies in high-quality epitaxial NiCo 2 O 4 thin films resulting from the complex energy landscape are reported. A strong out-of-plane magnetic anisotropy, linear magnetoresistance, and robust anomalous Hall effect above 300 K are observed in 5-30 unit cell NiCo 2 O 4 films. The anomalous Hall resistance exhibits a nonmonotonic temperature dependence th...

show abstract

mentioning

confidence: 86%

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo₂O₄ Thin Films

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Although epitaxial strain does not have a direct impact on the carrier density, it may modify the effective thickness of the SNNO channel through enhanced structural distortion. It has been shown in previous studies of correlated oxide thin films that the surface/interface layers exhibit enhanced oxygen octahedral rotation, which can suppress the lattice c / a ratio by up to 8% . The structural distortion, however, should be at the similar level for the single‐layer and bilayer channels grown on the same type of substrate.…”

mentioning

confidence: 91%

Interfacial Charge Engineering in Ferroelectric‐Controlled Mott Transistors

et al. 2017

View full text Add to dashboard Cite

Heteroepitaxial coupling at complex oxide interfaces presents a powerful tool for engineering the charge degree of freedom in strongly correlated materials, which can be utilized to achieve tailored functionalities that are inaccessible in the bulk form. Here, the charge-transfer effect between two strongly correlated oxides, Sm Nd NiO (SNNO) and La Sr MnO (LSMO), is exploited to realize a giant enhancement of the ferroelectric field effect in a prototype Mott field-effect transistor. By switching the polarization field of a ferroelectric Pb(Zr,Ti)O (PZT) gate, nonvolatile resistance modulation in the Mott transistors with single-layer SNNO and bilayer SNNO/LSMO channels is induced. For the same channel thickness, the bilayer channels exhibit up to two orders of magnitude higher resistance-switching ratio at 300 K, which is attributed to the intricate interplay between the charge screening at the PZT/SNNO interface and the charge transfer at the SNNO/LSMO interface. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy studies of SNNO/LSMO heterostructures reveal about 0.1 electron per 2D unit cell transferred between the interfacial Mn and Ni layers, which is corroborated by first-principles density functional theory calculations. The study points to an effective strategy to design functional complex oxide interfaces for developing high-performance nanoelectronic and spintronic applications.

show abstract

“…In previous studies, an emergent uniaxial contribution in LSMO films grown on (001)-oriented STO is associated with crystal distortions of the film where the tetragonal crystal structure of the tensile-strained film can be locally altered with the formation of an orthorhombic structure due to different rotation patterns of the MnO 6 octahedra to favor epitaxial growth [44,45]. In most of the cases, this is promoted by the substrate surface morphology (e.g., regular step-terrace structures, large miscut angle or lithographed periodic stripes) [15,17,18,45]. To observe if the large mismatch between the tensile-strained LSMO and BTO systems (≈2.35%) results in deformation of the LSMO atomic layers close to their interface, we performed a local strain study.…”

Section: Resultsmentioning

confidence: 99%

Observation of unexpected uniaxial magnetic anisotropy in La_2/3Sr_1/3MnO₃ films by a BaTiO₃ overlayer in an artificial multiferroic bilayer

Ordoñez¹,

Marín²,

Rodríguez³

et al. 2020

Beilstein J. Nanotechnol.

View full text Add to dashboard Cite

We studied in detail the in-plane magnetic properties of heterostructures based on a ferroelectric BaTiO3 overlayer deposited on a ferromagnetic La2/3Sr1/3MnO3 film grown epitaxially on pseudocubic (001)-oriented SrTiO3, (LaAlO3)0.3(Sr2TaAlO6)0.7 and LaAlO3 substrates. In this configuration, the combination of both functional perovskites constitutes an artificial multiferroic system with potential applications in spintronic devices based on the magnetoelectric effect. La2/3Sr1/3MnO3 single layers and BaTiO3/La2/3Sr1/3MnO3 bilayers using the pulsed-laser deposition technique. We analyzed the films structurally through X-ray reciprocal space maps and high-angle annular dark field microscopy, and magnetically via thermal demagnetization curves and in-plane magnetization versus applied magnetic field loops at room temperature. Our results indicate that the BaTiO3 layer induces an additional strain in the La2/3Sr1/3MnO3 layers close to their common interface. The presence of BaTiO3 on the surface of tensile-strained La2/3Sr1/3MnO3 films transforms the in-plane biaxial magnetic anisotropy present in the single layer into an in-plane uniaxial magnetic anisotropy. Our experimental evidence suggests that this change in the magnetic anisotropy only occurs in tensile-strained La2/3Sr1/3MnO3 film and is favored by an additional strain on the La2/3Sr1/3MnO3 layer promoted by the BaTiO3 film. These findings reveal an additional mechanism that alters the magnetic behavior of the ferromagnetic layer, and consequently, deserves further in-depth research to determine how it can modify the magnetoelectric coupling of this hybrid multiferroic system.

show abstract

Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

Cited by 42 publications

References 37 publications

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo₂O₄ Thin Films

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo₂O₄ Thin Films

Interfacial Charge Engineering in Ferroelectric‐Controlled Mott Transistors

Observation of unexpected uniaxial magnetic anisotropy in La_2/3Sr_1/3MnO₃ films by a BaTiO₃ overlayer in an artificial multiferroic bilayer

Contact Info

Product

Resources

About

Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

Cited by 42 publications

References 37 publications

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo2O4 Thin Films

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo2O4 Thin Films

Interfacial Charge Engineering in Ferroelectric‐Controlled Mott Transistors

Observation of unexpected uniaxial magnetic anisotropy in La2/3Sr1/3MnO3 films by a BaTiO3 overlayer in an artificial multiferroic bilayer

Contact Info

Product

Resources

About

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo₂O₄ Thin Films

Magnetotransport Anomaly in Room‐Temperature Ferrimagnetic NiCo₂O₄ Thin Films

Observation of unexpected uniaxial magnetic anisotropy in La_2/3Sr_1/3MnO₃ films by a BaTiO₃ overlayer in an artificial multiferroic bilayer