arXiv subjects

Yasemin Ozbek

Publications and source records attributed to Yasemin Ozbek.

5 recordsLinked to original sources

arXiv2026

Dual Charge-Density-Waves in Two-dimensional DyTe3 and Their Distinct Impacts on Magneto-Transport Properties

Charge-density-waves (CDWs) are macroscopic quantum states defined by periodic modulations in electronic charge density coupled with lattice distortions. Despite significant research efforts, the evolution of electromagnetic transport properties in the presence of CDWs remains largely unexplored. Here, we report the effects of two orthogonal CDWs (CDW1 and CDW2) coexisting at low-temperature in DyTe3 on its electronic transport properties. Importantly, we find that while no clear magnetotransport anomaly is resolved across CDW1 transition under the present experimental conditions, the emergence of CDW2 drives a drastic enhancement in magnetoresistance and a multiband-governed nonlinear Hall response. These results demonstrate that CDW1 and CDW2 in DyTe3 are fundamentally different and impact its electronic transport in qualitatively distinct ways, establishing DyTe3 as a model system for understanding the transport consequences of multiple CDWs in quasi-two-dimensional materials.

cond-mat.str-el↗

arXiv2024

Giant Nernst Angle in Self-Intercalated van der Waals Magnet Cr$_{1.25}$Te$_2$

The discovery of two-dimensional van der Waals (vdW) magnetic materials has propelled advancements in technological devices. The Nernst effect, which generates a transverse electric voltage in the presence of a longitudinal thermal gradient, shows great promise for thermoelectric applications. In this work, we report the electronic and thermoelectric transport properties of Cr$_{1.25}$Te$_2$, a layered self-intercalated vdW material which exhibits an antiferromagnetic ordering at TN ~ 191 K followed by a ferromagnetic-like phase transition at TC ~171 K. We observe a prominent topological Hall effect and topological Nernst effect between TC and TN, which is ascribable to non-coplanar spin textures inducing a real-space Berry phase due to competing ferromagnetic and antiferromagnetic interactions. Furthermore, we show that Cr$_{1.25}$Te$_2$ exhibits a substantial anomalous Nernst effect, featuring a giant Nernst angle of ~37% near TC and a maximum Nernst thermoelectric coefficient of 0.52 uV/K. These results surpass those of conventional ferromagnets and other two-dimensional vdW materials, highlighting Cr$_{1.25}$Te$_2$ as a promising candidate for advanced thermoelectric devices based on the Nernst effect.

cond-mat.mtrl-sci↗

arXiv2024

Distance-Dependent Evolution of Electronic States in Kagome- Honeycomb Lateral Heterostructures in FeSn

In this work, we demonstrate the formation and electronic influence of lateral heterointerfaces in FeSn containing Kagome and honeycomb layers. Lateral heterostructures offer spatially resolved property control, enabling the integration of dissimilar materials and promoting phenomena not typically observed in vertical heterostructures. Using the molecular beam epitaxy technique, we achieve a controllable synthesis of lateral heterostructures in the Kagome metal FeSn. With scanning tunneling microscopy/spectroscopy in conjunction with first-principles calculations, we provide a comprehensive understanding of the bonding motif connecting the Fe3Sn-terminated Kagome and Sn2-terminated honeycomb surfaces. More importantly, we reveal a distance-dependent evolution of the electronic states in the vicinity of the heterointerfaces. This evolution is significantly influenced by the orbital character of the flat bands. Our findings suggest an approach to modulate the electronic properties of the Kagome lattice, which should be beneficial for the development of future quantum devices.

cond-mat.str-el↗

arXiv2022

Superconducting Phase of $\mathrm{Ti_xO_y}$ Thin Films Grown by Molecular Beam Epitaxy

We investigate the complex relationship between the growth conditions and the structural and transport properties of $\mathrm{Ti_xO_y}$ thin films grown by molecular beam epitaxy. Transport properties ranging from metallicity to superconductivity and insulating states are stabilized by effectively tuning the O/Ti ratio via the Ti flux rate and the O partial pressure, $P_{Ox}$, for films grown on (0001)-$\mathrm{Al_2 O_3}$ substrates at 850$^{\circ}$ C. A cubic $c-\mathrm{TiO_{1\pmδ}}$ buffer layer is formed for low O/Ti ratios while a corundum cr-$\mathrm{Ti_2 O_3}$ layer is formed under higher oxidizing conditions. Metallicity is observed for c-$\mathrm{TiO_{1-δ}}$ buffer layers. The superconducting $\mathrm{γ-Ti_3 O_5}$ Magnéli phase is found to nucleate on a c-$\mathrm{TiO_{1-δ}}$ buffer for intermediate $P_{Ox}$ conditions and an insulator-superconducting transition is observed at 4.5 K (T$_C^{onset}=6 K$) for 85 nm thick films. Strain relaxation of the $\mathrm{γ-Ti_3 O_5}$ occurs with increasing film thickness and correlates with a thickness-dependent increase in T$_C$ observed for $\mathrm{Ti_xO_y}$ thin films.

cond-mat.supr-con↗

arXiv2020

Interface-driven magnetic anisotropy in relaxed La$_{0.7}$Sr$_{0.3}$CrO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ heterostructures on MgO

We investigate the structural and magnetic properties of La$_{0.7}$Sr$_{0.3}$CrO$_3$ (LSCO)/La$_{0.7}$Sr$_{0.3}$MnO$_3$(LSMO) heterostructures grown on (001)-oriented MgO by molecular beam epitaxy. Due to the large film-substrate lattice mismatch, strain relaxation is found to occur within the first 2-3 unit cells (uc) of the film as evidenced by reflection high energy electron diffraction and high-resolution synchrotron X-ray reciprocal space mapping. We find that the presence of the LSCO spacer and capping layers leads to ferromagnetism in ultra-thin LSMO layers with thicknesses on the order of 2 uc with the magnetic easy axis oriented in the film plane. Net magnetic moments of 1.4 and 2.4 $μ_B$/Mn are measured for [2 uc LSCO/ 2 uc LSMO] and [2 uc LSCO/ 4 uc LSMO] superlattices, respectively by SQUID magnetometry. The effective magnetic anisotropy of the relaxed [2 uc LSCO/ 4 uc LSMO] heterostructure is found to be an order of magnitude higher than bulk LSMO highlighting the critical role of interfacial magnetic exchange interactions in tuning magnetic anisotropy at complex oxide interfaces.

cond-mat.mtrl-sci↗