arXiv subjects

Ersoy Şaşıoğlu

Publications and source records attributed to Ersoy Şaşıoğlu.

7 recordsLinked to original sources

arXiv2026

Orbital Hall effect and orbital altermagnetism in even- and odd-parity-wave magnetic Lieb lattices

Altermagnets combine compensated antiferromagnetic order with ferromagnet-like signatures such as spin-polarized bands and, under appropriate conditions, an anomalous Hall response. Their characteristic momentum-dependent spin splitting originates from the interplay of magnetic order and crystal structure and therefore does not require spin-orbit coupling (SOC), whereas the anomalous Hall effect relies on SOC. This raises the question whether the ferromagnet-like transport character of altermagnets can manifest already in the nonrelativistic limit. Here, we investigate the transport of orbital angular momentum in magnetic Lieb lattices. We show that a collinear antiferromagnetic texture realizes a d-wave altermagnetic state and simultaneously generates an orbital Hall effect, both in the complete absence of SOC. In this nonrelativistic limit, the orbital Hall response closely resembles that of the corresponding ferromagnet. When SOC is included, the orbital Hall effect is accompanied by a spin Hall response, while the altermagnetic spin texture acquires a corresponding orbital texture, realizing orbital altermagnetism. In contrast, an anomalous, or crystal, Hall effect requires SOC and is additionally subject to crystal-symmetry constraints. We extend the analysis from d-wave altermagnetism to odd-parity p-wave magnetism, where the orbital Hall effect becomes anisotropic and the orbital conductivity tensor develops a symmetric transverse component analogous to the planar Hall response in charge transport. Our results establish the orbital Hall effect as a nonrelativistic transport manifestation of the close relation between altermagnets and ferromagnets and extend this connection to unconventional magnetic orders beyond altermagnetism.

cond-mat.str-el↗

arXiv2026

Exact theory of chirality-dependent p-wave magnetism and Edelstein effect in spin spirals

Spin-momentum locking is widely regarded as a hallmark of relativistic spin-orbit coupling. Here we demonstrate analytically that it can instead emerge solely from magnetic chirality. Solving the minimal tight-binding model of electrons coupled to a spin spiral using a generalized Bloch theorem, we show that the spiral generates chirality-dependent p-wave magnetism characterized by the antisymmetric spin texture $\boldsymbol{s}(\boldsymbol{k})=-\boldsymbol{s}(-\boldsymbol{k})$. The exact solution further yields closed-form expressions for the electrical conductivity and the spin Edelstein susceptibility, revealing a microscopic mechanism by which magnetic chirality alone can generate spin polarization without spin-orbit coupling, with direct implications also for chirality-induced spin selectivity. In the strong exchange-coupling regime, the spin-dependent physics of the spin spiral becomes directly analogous to the orbital-dependent physics of electrons propagating through a non-magnetic helix. Our work establishes a minimal exactly solvable model of chirality-induced spin-momentum locking and spin-charge conversion beyond the conventional spin-orbit coupled paradigm.

cond-mat.mes-hall↗

arXiv2026

Coupled Spin-Orbital $p$-Wave Magnetism via Structural and Magnetic Chirality

Helical spin textures represent the minimal realization of $p$-wave magnetism which is characterized by momentum-odd spin polarization. Independently, structurally chiral crystals exhibit momentum-odd orbital polarization arising from broken inversion symmetry. Here, we demonstrate that spin-orbit coupling couples these two independent microscopic chirality degrees of freedom, allowing the orbital polarization of a chiral crystal to generate an additional contribution to the $p$-wave spin splitting. The resulting spin-orbital state is naturally classified by the relative chirality $η=χ_{\mathrm c}χ_{\mathrm m}$, giving rise to two symmetry-distinct $p$-wave phases corresponding to homochiral and heterochiral configurations which can be directly probed by the longitudinal conductivity. These phases exhibit distinct transport signatures, establishing a unified framework linking orbitronics and unconventional magnetism through coupled spin-orbital $p$-wave order.

cond-mat.mes-hall↗

arXiv2025

MIM-Diode-Like Rectification in Lateral 1T/1H/1T-MoS$_2$ Homojunctions via Interfacial Dipole Engineering

Lateral two-dimensional (2D) tunnel diodes that reproduce metal-insulator-metal (MIM)-diode-like rectification without using dissimilar contacts are attractive for scalable nanoelectronics. MoS$_2$ can exist in both the semiconducting 1H phase and the metallic 1T phase, enabling phase-engineered homojunctions within a single material. First-principles electronic structure and quantum transport calculations show that phase-engineered 1T/1H/1T--MoS$_2$ homojunctions exhibit pronounced MIM-diode-like rectification originating from interfacial charge transfer at asymmetric 1T/1H interfaces. The charge transfer establishes interface dipole steps that impose a built-in potential drop across the 1H barrier, thereby generating a trapezoidal tunnel barrier at zero bias. In contrast, symmetric 1T/1H interfaces do not form interface dipoles and show no rectification. To clarify the microscopic origin, a lateral graphene/hexagonal-boron-nitride/graphene junction is analyzed as a minimal MIM diode analogue with a simple interface and well-defined barrier, confirming that interface-induced dipoles, rather than work-function difference, enable the effect. The mechanism operates entirely within a single monolayer material system and does not rely on out-of-plane stacking, highlighting compatibility with phase patterning in 2D semiconductors. These results establish lateral 1T/1H/1T--MoS$_2$ as a fully 2D, single-material platform for MIM-diode-like rectification and position interface-dipole engineering as a general strategy for ultrathin in-plane diodes, high-frequency detectors, and energy-harvesting tunnel devices.

cond-mat.mtrl-sci↗

arXiv2025

Multifunctional steep-slope spintronic transistors with spin-gapless-semiconductor or spin-gapped-metal electrodes

Spin-gapless semiconductors (SGSs) are a promising class of materials for spintronic applications, enabling functions beyond conventional electronics. This study introduces a novel design for multifunctional spintronic field-effect transistors (FETs) using SGSs and/or spin-gapped metals (SGMs) as source and drain electrodes. These devices operate similarly to metal-semiconductor Schottky barrier FETs, where a potential barrier forms between the SGS (or SGM) electrode and the semiconducting channel. Unlike traditional Schottky barrier FETs, these devices utilize the unique spin-dependent transport properties of SGS/SGM electrodes to achieve sub-60 mV/dec switching, overcoming the 60 mV/dec sub-threshold swing limit in MOSFETs for low-voltage operation. Additionally, SGMs contribute a negative differential resistance (NDR) effect with an ultra-high peak-to-valley current ratio. The proposed spintronic FETs combine sub-60 mV/dec switching, non-local giant magnetoresistance (GMR), and NDR, making them suitable for applications like logic-in-memory computing and multivalued logic. These properties support computing architectures beyond the von-Neumann model, enabling efficient data processing. Two-dimensional (2D) nanomaterials provide a promising platform for these multifunctional FETs. We screen a computational 2D materials database to identify suitable SGS and SGM materials, selecting VS$2$ as the SGS for simulations. Using a non-equilibrium Green's function method with density functional theory, we simulate transfer ($I{\mathrm{D}}$-$V_{\mathrm{G}}$) and output ($I_{\mathrm{D}}$-$V_{\mathrm{D}}$) characteristics of a VS$_2$/Ga$_2$O$_2$ FET based on 2D type-II SGS VS$_2$, predicting a sub-threshold swing of 20 mV/dec, a high on/off ratio of 10$^8$, and a notable non-local GMR effect, demonstrating potential for low-power, high-performance applications.

cond-mat.mtrl-sci↗

arXiv2021

Externally controlled and switchable 2D electron gas at the Rashba interface between ferroelectrics and heavy $d$ metals

Strong spin-orbit coupling in noncentrosymmetric materials and interfaces results in remarkable physical phenomena, such as nontrivial spin textures, which may exhibit Rashba, Dresselhaus, and other intricated configurations. This provides a promising basis for nonvolatile spintronic devices and further implications. Here, we simulate from first principles a two-dimensional electron gas in ultrathin platinum and palladium layers grown on ferroelectric PbTiO$_3$(001). The latter allows, in principle, to switch and control the spin-to-charge conversion by the polarization reversal. We show how the band structure and its Rashba splitting differ in the Pt and Pd overlayers and how these electronic features change with increasing the overlayer thickness and upon reversal of polarization. Besides, for both overlayers, we simulated their current-voltage ($I-V$) characteristics, the resistance of which upon the polarization reversal changes between 20% and several hundred percent. The reported findings can be used to model directly the Rashba-Edelstein effect.

cond-mat.mes-hall↗

arXiv2020

First-principles study of the electronic and magnetic properties of cubic GdCu compound

The structural, electronic, and magnetic properties of bulk GdCu (CsCl-type) are investigated using spin density functional theory, where highly localized $4f$ orbitals are treated within LDA+$U$ and GGA+$U$ methods. The calculated magnetic ground state of GdCu using collinear as well as spin spiral calculations exhibits a C-type antiferromagnetic configuration representing a spin spiral propagation vector $\mathbf{Q}=\frac{2π}{a}(\frac{1}{2},\frac{1}{2},0)$. The parameters of the effective Heisenberg Hamiltonian are evaluated from a self-consistent electronic structure and are used to determine the magnetic transition temperature. The estimated Néel temperature of the cubic GdCu using GGA+$U$ and LDA+$U$ density functionals within the mean field and random phase approximations are in good agreement with the experimentally measured values. In particular, the theoretical understanding of the experimentally observed core Gd $4f$ levels shifting in photoemission spectroscopy experiments is investigated in detail. By employing the self-consistent constrained random-phase approximation we determined the strength of the effective Coulomb interaction (Hubbard $U$) between localized $4f$ electrons. We find that, the shift of Gd-$4f$ states in GdCu with respect to bulk Gd within DFT+$U$ is sensitive to choice of lattice parameter. The calculations for $4f$-level shifts using DFT+$U$ methods as well as Hubbard-1 approximation are not consistent with the experimental findings.

cond-mat.str-el↗