arXiv subjects

Zhaoliang Liao

Publications and source records attributed to Zhaoliang Liao.

At least 19 recordsLinked to original sources

arXiv2026

Interface Spin-orbit Coupling Induced Room-temperature Ferromagnetic Insulator

Fabricating room-temperature ferromagnetic insulators, which are crucial candidates for next-generation dissipation-free quantum and spintronic devices, remains a significant challenge. In this Letter, we report on the epitaxial synthesis of novel room-temperature ferromagnetic insulating thin films created through the precise construction of (111)-oriented 3d/5d interfaces. Our analysis indicates that, unlike conventional doping methods, the (111)-oriented SrIrO3/La2/3Sr1/3MnO3 (SIO/LSMO) interfaces exhibit markedly enhanced spin-orbit coupling. This enhanced interfacial spin-orbit coupling strengthens the electron-phonon coupling in LSMO, thereby shortening the electronic mean free path. As a result, the intrinsic metallicity of LSMO is suppressed, giving rise to a new ferromagnetic insulating phase that emerges between the ferromagnetic metal and paramagnetic insulator regimes of the LSMO phase diagram. Furthermore, the temperature window of the ferromagnetic insulating phase can be tuned by precisely controlling the thickness of the LSMO layers. Our Letter reveals a new strategy for developing ferromagnetic insulators by engineering 3d/5d interfaces and orientations, paving a way for the development of novel dissipation-free quantum and spintronic devices.

cond-mat.str-el↗

arXiv2025

Ultrathin oxide freestanding membranes with large-scale continuity and structural perfection

Freestanding oxide membranes offer integration with advanced semiconductor platforms, unlocking opportunities for flexible electronics, silicon-based spintronics, neuromorphic computing, and high-performance energy technologies. Scalable fabrication of such membranes is essential for bridging fundamental discoveries in complex oxides with practical device deployment. However, the lateral dimensions of crack- and wrinkle-free membranes remain limited to millimeter scales, forming a critical bottleneck for large-area architectures. Overcoming this challenge demands strategies that preserve crystalline quality while suppressing defect transfer during release. Here, we demonstrate an approach based on a water-soluble sacrificial layer of super-tetragonal Sr4Al2O7, enabling the fabrication of ultrathin, crack-free, and wrinkle-free free-standing oxide membranes spanning centimeter-scale areas. This method is broadly applicable to a wide range of oxides and establishes a new pathway toward large-scale silicon integration and flexible oxide technologies. Nevertheless, dissolution of the sacrificial layer introduces oxygen vacancies into the SrRuO3 membranes, with diffusion depths reaching six unit cells, leading to anomalous "up-and-down" transport behavior. Although post-annealing can eliminate these vacancies, the required temperatures are incompatible with CMOS processes. Therefore, ultrathin freestanding membranes fabricated by water-assisted lift-off still face critical challenges for integration into miniaturized silicon-based oxide devices.

cond-mat.mtrl-sci↗

arXiv2025

Time-Reversal Symmetry Protected Transport at Correlated Oxide Interfaces

Time-reversal symmetry (TRS) protection is core to topological physics, yet its role in correlated oxides-typically non-topological-remains underexplored. This limit hampers the potential in engineering exotic quantum states by fusing TRS protection and the rich emergent phenomena in the oxide platform. Here, we report evidence of a TRS-protected subband at oxygen vacancy-free LaAlO3/SrTiO3 interfaces. This subband causes a low-field quantum oscillation with anomalous characters: exceptionally light electron mass, aperiodicity, and susceptibility to magnetic fields. All findings align with a Rashba model in which TRS-protected transport occurs along quasi-1D ferroelastic domain walls, which possess a Dirac band topology and a giant Rashba spin-orbit coupling, two orders stronger than the 2D interface. Our results deepen the understanding of SrTiO3-based electron systems, unveiling an appealing new platform for quantum engineering.

cond-mat.mes-hall↗

arXiv2022

Emergence of insulating ferrimagnetism and perpendicular magnetic anisotropy in 3d-5d perovskite oxide composite films for insulator spintronic

Magnetic insulators with strong perpendicular magnetic anisotropy (PMA) play a key role in exploring pure spin current phenomena and developing ultralow-dissipation spintronic devices, thereby it is highly desirable to develop new material platforms. Here we report epitaxial growth of La2/3Sr1/3MnO3 (LSMO)-SrIrO3 (SIO) composite oxide films (LSMIO) with different crystalline orientations fabricated by sequential two-target ablation process using pulsed laser deposition. The LSMIO films exhibit high crystalline quality with homogeneous mixture of LSMO and SIO at atomic level. Ferrimagnetic and insulating transport characteristics are observed, with the temperature-dependent electric resistivity well fitted by Mott variable-range-hopping model. Moreover, the LSMIO films show strong PMA. Through further constructing all perovskite oxide heterostructures of the ferrimagnetic insulator LSMIO and a strong spin-orbital coupled SIO layer, pronounced spin Hall magnetoresistance (SMR) and spin Hall-like anomalous Hall effect (SH-AHE) were observed. These results illustrate the potential application of the ferrimagnetic insulator LSMIO in developing all-oxide ultralow-dissipation spintronic devices.

cond-mat.mtrl-sci↗

arXiv2021

Strain-induced atomic-scale building blocks for ferromagnetism in epitaxial LaCoO3

The origin of strain-induced ferromagnetism, which is robust regardless of the type and degree of strain in LaCoO3 (LCO) thin films, is enigmatic despite intensive research efforts over the past decade. Here, by combining scanning transmission electron microscopy with ab initio density functional theory plus U calculations, we report that the ferromagnetism does not emerge directly from the strain itself, but rather from the creation of compressed structural units within ferroelastically formed twin-wall domains. The compressed structural units are magnetically active with the rocksalt-type high-spin/low-spin order. Our study highlights that the ferroelastic nature of ferromagnetic structural units is important for understanding the intriguing ferromagnetic properties in LCO thin films.

cond-mat.mtrl-sci↗

arXiv2021

Observation of an Unusual Colossal Anisotropic Magnetoresistance Effect in an Antiferromagnetic Semiconductor

Searching for novel antiferromagnetic materials with large magnetotransport response is highly demanded for constructing future spintronic devices with high stability, fast switching speed, and high density. Here we report a colossal anisotropic magnetoresistance effect in an antiferromagnetic binary compound with layered structure rare-earth dichalcogenide EuTe2. The AMR reaches 40000%, which is 4 orders of magnitude larger than that in conventional antiferromagnetic alloys. Combined magnetization, resistivity, and theoretical analysis reveal that the colossal AMR effect is attributed to a novel mechanism of vector-field tunable band structure, rather than the conventional spin-orbit coupling mechanism. Moreover, it is revealed that the strong hybridization between orbitals of Eu-layer with localized spin and Te-layer with itinerant carriers is extremely important for the large AMR effect. Our results suggest a new direction towards exploring AFM materials with prominent magnetotransport properties, which creates an unprecedented opportunity for AFM spintronics applications.

cond-mat.mtrl-sci↗

arXiv2019

Growing a LaAlO3/SrTiO3 heterostructure on Ca2Nb3O10 nanosheets

The two-dimensional electron liquid which forms between the band insulators LaAlO3 (LAO) and SrTiO3 (STO) is a promising component for oxide electronics, but the requirement of using single crystal SrTiO3 substrates for the growth limits its applications in terms of device fabrication. It is therefore important to find ways to deposit these materials on other substrates, preferably Si, or Si-based, in order to facilitate integration with existing technology. Interesting candidates are micron-sized nanosheets of Ca2Nb3O10 which can be used as seed layers for perovskite materials on any substrate. We have used low-energy electron microscopy (LEEM) with in-situ pulsed laser deposition to study the subsequent growth of STO and LAO on such flakes which were deposited on Si. We can follow the morphology and crystallinity of the layers during growth, as well as fingerprint their electronic properties with angle resolved reflected electron spectroscopy. We find that STO layers, deposited on the nanosheets, can be made crystalline and flat; that LAO can be grown in a layer-by-layer fashion; and that the full heterostructure shows the signature of the formation of a conducting interface.

cond-mat.mtrl-sci↗

arXiv2019

Electronic structure of rare-earth infinite-layer ReNiO2 (Re=La, Nd)

The discovery of infinite layer nickelate superconductor marks the new era in the field of superconductivity. In the rare-earth (Re) nickelates ReNiO2, although the Ni is also of d9 electronic configuration, analogous to Cu d9 in cuprates, whether electronic structures in infinite-layer nickelate are the same as cuprate and possess the single band feature as well are still open questions. To illustrate the electronic structure of rare-earth infinite-layer nickelate, we perform first principle calculations of LaNiO2 and NdNiO2 compounds and compare them with that of CaCuO2 using hybrid functional method together with Wannier projection and group symmetry analysis. Our results indicate that the Ni-dx2-y2 in the LaNiO2 has weak hybridization with other orbitals and exhibits characteristic single band feature, whereas in NdNiO2, the Nd-f orbital hybridizes with Ni-dx2-y2 and is a non-negligible ingredient for transport and even high-temperature superconductivity. Given that the Cu-dx2-y2 in cuprate strongly hybridizes with O-2p, the calculated band structures of nickelate imply some new band characters which is worth to gain more attentions.

cond-mat.supr-con↗

arXiv2019

Competing Phases in Epitaxial Vanadium Dioxide at Nanoscale

Phase competition in correlated oxides offers tantalizing opportunities as many intriguing physical phenomena occur near the phase transitions. Owing to a sharp metal-insulator transition (MIT) near room temperature, correlated vanadium dioxide (VO2) exhibits a strong competition between insulating and metallic phases that is important for practical applications. However, the phase boundary undergoes strong modification when strain is involved, yielding complex phase transitions. Here, we report the emergence of the nanoscale M2 phase domains in VO2 epitaxial films under anisotropic strain relaxation. The phase states of the films are imaged by multi-length-scale probes, detecting the structural and electrical properties in individual local domains. Competing evolution of the M1 and M2 phases indicates a critical role of lattice-strain on both the stability of the M2 Mott phase and the energetics of the MIT in VO2 films. This study demonstrates how strain engineering can be utilized to design phase states, which allow deliberate control of MIT behavior at the nanoscale in epitaxial VO2 films.

cond-mat.str-el↗

arXiv2019

Spin chirality fluctuation in two-dimensional ferromagnets with perpendicular anisotropy

Non-coplanar spin textures with scalar spin chirality can generate effective magnetic field that deflects the motion of charge carriers, resulting in topological Hall effect (THE), a powerful probe of the ground state and low-energy excitations of correlated systems. However, spin chirality fluctuation in two-dimensional ferromagnets with perpendicular anisotropy has not been considered in prior studies. Herein, we report direct evidence of universal spin chirality fluctuation by probing the THE above the transition temperatures in two different ferromagnetic ultra-thin films, SrRuO$_3$ and V doped Sb$_2$Te$_3$. The temperature, magnetic field, thickness, and carrier type dependences of the THE signal, along with our Monte-Carlo simulations, unambiguously demonstrate that the spin chirality fluctuation is a universal phenomenon in two-dimensional Ising ferromagnets. Our discovery opens a new paradigm of exploring the spin chirality with topological Hall transport in two-dimensional magnets and beyond

cond-mat.mtrl-sci↗

arXiv2019

Surface and Interface Properties of La2/3Sr1/3MnO3 Thin Films on SrTiO3 (001)

Understanding and manipulating properties emerging at a surface or an interface require a thorough knowledge of structure-property relationships. We report a study of a prototype oxide system, La2/3Sr1/3MnO3 grown on SrTiO3(001), by combining in-situ angle-resolved x-ray photoelectron spectroscopy, ex-situ x-ray diffraction, and scanning transmission electron microscopy/spectroscopy with electric transport measurements. We find that La2/3Sr1/3MnO3 films thicker than 20 unit cells (u.c.) exhibit a universal behavior with no more than one u.c. intermixing at the interface but at least 3 u.c. of Sr segregation near the surface which is (La/Sr)O terminated. The conductivity vs film thickness shows the existence of nonmetallic layers with thickness ~ 6.5 +/- 0.9 u.c., which is independent of film thickness but mainly relates to the deviation of Sr concentration near the surface region. Below 20 u.c., the surface of the films appears mixed (La/Sr)O with MnO2 termination. Decreasing film thickness to less than 10 u.c. leads to the enhanced deviation of chemical composition in the films and eventually drives the film insulating. Our observation offers a natural explanation for the thickness-driven metal-nonmetal transition in thin films based on the variation of film stoichiometry.

cond-mat.str-el↗

arXiv2019

Exploiting symmetry-mismatch to control magnetism in a ferroelastic heterostructure

In the bulk, LaCoO3 (LCO) is a paramagnet, yet in tensile strained thin films at low temperature ferromagnetism (FM) is observed, and its origin remains unresolved. Polarized neutron reflectometry (PNR) is a powerful tool to determine the depth profiles of the structure and magnetization simultaneously and thus the evolution of the interfacial FM with strain can be accurately revealed. Here we quantitatively measured the distribution of atomic density and magnetization in LCO films by PNR and found that the LCO layers near the heterointerfaces exhibit a reduced magnetization but an enhanced atomic density, whereas the interior shows the opposite trend. We attribute the nonuniformity to the symmetry mismatch at the interface, which induces a structural distortion related to the ferroelasticity of LCO. This assertion is tested by systematic application of hydrostatic pressure during the PNR experiments. These results provide unique insights into mechanisms driving FM in strained LCO films while offering a tantalizing observation that tunable deformation of the CoO6 octahedra in combination with the ferroelastic order parameter.

cond-mat.mtrl-sci↗

arXiv2019

Nanoscale ferroelastic twins formed in strained LaCoO3 films

The coexistence and coupling of ferroelasticity and magnetic ordering in a single material offers a great opportunity to realize novel devices with multiple tuning knobs. Complex oxides are a particularly promising class of materials to find multiferroic interactions as they often possess rich phase diagrams and the interactions are very sensitive to external perturbations. Still, there are very few examples of these systems. Here we report the observation of twinning domains in ferroelastic LaCoO3 epitaxial thin films and their geometric control of structural symmetry that are intimately linked to the material electronic and magnetic states. A unidirectional structural modulation is achieved by selective choice of substrates possessing two-fold rotational symmetry. This modulation perturbs the crystal field splitting energy, leading to unexpected in plane anisotropy of orbital configuration and magnetization. These findings demonstrate the utilization of structural modulation to control multiferroic interactions and may enable a great potential for stimulation of exotic phenomena through artificial domain engineering.

cond-mat.mtrl-sci↗

arXiv2018

Spin direction controlled electronic band structure in two dimensional ferromagnetic CrI3

Manipulating physical properties using the spin degree of freedom constitutes a major part of modern condensed matter physics and is very important for spintronics devices. Using the newly discovered two dimensional van der Waals ferromagnetic CrI3 as a prototypic material, we theoretically demonstrated a giant magneto band-structure (GMB) effect whereby a change of magnetization direction significantly modifies the electronic band structure. Our density functional theory calculations and model analysis reveal that rotating the magnetic moment of CrI3 from out-of-plane to in-plane causes a direct-to-indirect bandgap transition, inducing a magnetic field controlled photoluminescence. Moreover, our results show a significant change of Fermi surface with different magnetization directions, giving rise to giant anisotropic magnetoresistance. Additionally, the spin reorientation is found to modify the topological states. Given that a variety of properties are determined by band structures, our predicted GMB effect in CrI3 opens a new paradigm for spintronics applications.

cond-mat.mtrl-sci↗

arXiv2017

Quantum Anomalous Hall State in Ferromagnetic SrRuO$_3$ (111) Bilayers

SrRuO$_3$ heterostructures grown in the (111) direction are a rare example of thin film ferromagnets. By means of density functional theory plus dynamical mean field theory we show that the half-metallic ferromagnetic state with an ordered magnetic moment of 2$μ_{B}$/Ru survives the ultimate dimensional confinement down to a bilayer, even at elevated temperatures of 500$\,$K. In the minority channel, the spin-orbit coupling opens a gap at the linear band crossing corresponding to $\frac34$ filling of the $t_{2g}$ shell. We demonstrate that the respective state is Haldane's quantum anomalous Hall state with Chern number $C$=1, without an external magnetic field or magnetic impurities.

cond-mat.str-el↗

arXiv2017

Thickness dependent properties in oxide heterostructures driven by structurally induced metal-oxygen hybridization variations

Thickness driven electronic phase transitions are broadly observed in different types of functional perovskite heterostructures. However, uncertainty remains whether these effects are solely due to spatial confinement, broken symmetry or rather to a change of structure with varying film thickness. Here, we present direct evidence for the relaxation of oxygen 2p and Mn 3d orbital (p-d) hybridization coupled to the layer dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced Curie temperature is achieved by reducing the octahedral tilting via interface structure engineering. Atomically resolved lattice, electronic and magnetic structures together with X-ray absorption spectroscopy demonstrate the central role of thickness dependent p-d hybridization in the widely observed dimensionality effects present in correlated oxide heterostructures.

cond-mat.mtrl-sci↗

arXiv2017

Delicate competing electronic states in ultrathin manganite films

The coupling between the electrical transport properties of La2/3Sr1/3MnO3 (LSMO) thin films and structural phase transitions of SrTiO3 (STO) substrates at Ts = 105 K has been investigated. We found that the electrical resistivity of LSMO films exhibit a cusp at Ts, which is greatly amplified by tuning films to the verge of metallic and insulating phases, i.e., to the boundary of two delicate competing electronic states. Our results demonstrate that small amounts of strain can tip the subtle balance of competing interactions and tune the electronic properties in correlated electron materials.

cond-mat.mtrl-sci↗

arXiv2016

Interface Engineering in La0.67Sr0.33MnO3-SrTiO3 Heterostructures

Interface engineering is an extremely useful tool for systematically investigating materials and the various ways materials interact with each other. We describe different interface engineering strategies designed to reveal the origin of the electric and magnetic dead-layer at La0.67Sr0.33MnO3 interfaces. La0.67Sr0.33MnO3 is a key example of a strongly correlated peroskite oxide material in which a subtle balance of competing interactions gives rise to a ferromagnetic metallic groundstate. This balance, however, is easily disrupted at interfaces. We systematically vary the dopant profile, the disorder and the oxygen octahedra rotations at the interface to investigate which mechanism is responsible for the dead layer. We find that the magnetic dead layer can be completely eliminated by compositional interface engineering such that the polar discontinuity at the interface is removed. This, however, leaves the electrical dead-layer largely intact. We find that deformations in the oxygen octahedra network at the interface are the dominant cause for the electrical dead layer.

cond-mat.mtrl-sci↗