arXiv subjects

Bumned Soodchomshom

Publications and source records attributed to Bumned Soodchomshom.

18 recordsLinked to original sources

arXiv2026

A Quantum-Inspired Framework for Subjective Evaluation: Cognitive Polarization and Entropic Measures

We propose a quantum-inspired framework to model subjective evaluation processes using state vectors in Hilbert space. In this approach, individual preferences are represented as cognitive states polarized between 'like' and 'dislike', enabling a continuous interpretation of evaluative attitudes. The evolution of these states is characterized on the Bloch sphere, and the cognitive coherence is interpreted geometrically. To further analyze the uncertainty and diversity in subjective preferences, we introduce both Shannon entropy (at the individual level) and Von Neumann entropy (at the group level) into the framework. A small-scale simulated dataset is used to conceptually demonstrate how these entropy measures can reveal internal indecisiveness and collective incoherence. The model offers a physically grounded and mathematically expressive tool for quantifying subjectivity.

cond-mat.mes-hall↗

arXiv2025

Strain-Tuned Optical Properties of a Two-Dimensional Hexagonal Lattice: Exploiting Saddle Degrees of Freedom and Saddle Filtering Effects

The deformation of hexagonal lattices has attracted considerable attention due to its promising applications in straintronics. This study employs the tight-binding model to investigate the anisotropic spectrum, where electronic transport can be manipulated by the degree of deformation. The longitudinal conductivities, light transmittance, and absorbance are analyzed, revealing enhancement along one direction and suppression along the other. The findings indicate that the direction and magnitude of strain can be determined by measuring transmittance and absorbance, showing significant deviations from the unstrained condition. Furthermore, a strong absorbance is observed due to the interband transition of electrons near the M-point saddles, linked to van Hove singularities for specific values of nearest and next-nearest hoping energy. The unexpected characteristics of saddle polarization-analogous to valley polarization at K- and K'-become particularly prominent when strain affects the selection of M-point saddle. Notably, the demonstration indicates that a highly efficient M-point saddle filtering effect takes place, induced by linearly polarized light. This model paves the way for exploring the optical properties of anisotropic hexagonal lattices, such as black phosphorus and borophene oxide. These results also open a pathway to strain-programmable optoelectronic devices, such as polarization-selective photodetectors, tunable absorbers, and ultrathin optical filters.

cond-mat.mes-hall↗

arXiv2025

Particle-Hole Creation in Condensed Matter: A Conceptual Framework for Modeling Money-Debt Dynamics in Economics

We propose a field-theoretic framework that models money-debt dynamics in economic systems through a direct analogy to particle-hole creation in condensed matter physics. In this formulation, issuing credit generates a symmetric pair-money as a particle-like excitation and debt as its hole-like counterpart-embedded within a monetary vacuum field. The model is formalized via a second-quantized Hamiltonian that incorporates time-dependent perturbations to represent real-world effects such as interest and profit, which drive asymmetry and systemic imbalance. This framework successfully captures both macroeconomic phenomena, including quantitative easing (QE) and gold-backed monetary regimes, and microeconomic credit creation, under a unified quantum-like formalism. In particular, QE is interpreted as generating entangled-like pairs of currency and bonds, exhibiting systemic correlations akin to nonlocal quantum interactions. Asset-backed systems, on the other hand, are modeled as coherent superpositions that collapse upon use. This approach provides physicists with a rigorous and intuitive toolset to analyze economic behavior using many-body theory, laying the groundwork for a new class of models in econophysics and interdisciplinary field analysis.

econ.GN↗

arXiv2024

Triplet fermions in MXenes: The Applications for spintronic-based devices

We investigate the electronic properties of MXenes by three bands tight-binding model of \d_{z^2} , \d_{xy} , and \d_{x^2-y^2} orbitals. The three corresponding bands touch each other at high symmetry K point in the case of absence of spin-orbit interaction. The proper parameters can be obtained by Slater-Koster parameters related to chemical bonding, π, σ, and δbonds. The model calculated for these band structures make an agreement with the same trend as discussed in DFT calculation which the hopping parameters may be identified roughly by fermi velocity. Furthermore, the triplet fermion occurs around K point hosting by flat band, leading to super-Klein tunnelling and anti-super-Klein tunnelling for gapped and gapless pseudospin-1 fermion, respectively. These may apply for nanodevices operated by spin polarization which is more stable than that of the conventional two-dimensional materials.

cond-mat.mtrl-sci↗

arXiv2023

Spin-valley Hall effects and pseudospin-1 system in transition-metal dichalcogenides: three band model approach

The energy spectra of transition metal dichalcogenides are primarily influenced by the and orbitals. This results in a three-band model characterized by strong spin-orbit interaction. Investigating these bands using a projection into a two-band model is adequate for exploring electronic and optical properties. The topological phases, spin-valley Hall effect, derived from spin-valley Chern numbers, are also examined. The inclusion of spin-orbit interaction breaks inversion symmetry while maintaining time-reversal symmetry. This leads to the non-zero spin-valley dependent Hall conductivities, pivotal for both the spin Hall and valley Hall effects. These phenomena could have applications beyond traditional electronics, potentially encoding quantum bits. In particular, electrons at high-symmetry points, namely the K and K' points, might behave as if they are in a pseudospin-1 system with spin angular momentum of and , leading to triplet energy states. Such predictions could encourage super-Klein tunneling, which might offer insights into Majorana fermions, relevant for topological quantum computation.

cond-mat.mes-hall↗

arXiv2023

Control of valley optical conductivity and topological phases in buckled hexagonal lattice by orientation of in-plane magnetic field

We investigate the optical conductivity, along with longitudinal and transverse conductivities, in buckled hexagonal lattice such as silicene subjected to both an in-plane magnetic field and a perpendicular electric field. In this model, we neglect the effect of the spin-orbit interaction, which is of a smaller order compared to the strong staggered potential and the next-nearest hoping energy. The orientations of the in-plane magnetic field and the perpendicular electric field give rise to a non-uniform, tunable gap. The Chern number for each valley degree of freedom deviates from being constant but remains steady when summed over the entire Brillouin zone. The longitudinal and transverse currents, in the case of a specific valley, can be selected by adjusting the direction of the electric field in the semimetal phase. Furthermore, the defining characteristics of topological phases induces the rapid change in longitudinal conductivity when varying the angle of orientation of the in-plane magnetic field under monochromatic light, and perfect valley filtering in transverse conductivity. The transverse current associated with a specific valley can be selected when the angle of orientation satisfies the specific conditions. This investigation paves the way for materials design with valley-locked current, using a specific orientation of the in-plane magnetic field.

cond-mat.mes-hall↗

arXiv2019

Nearly pure spin-valley sideband tunneling in silicene: effect of interplay of time periodic potential barrier and spin-valley-dependent Dirac mass

We study massive Dirac fermion tunneling through time periodic potential in a silicene-based N-TP-N junction, where Ns are normal silicene regions and TP is the time periodic potential barrier. The fermions would absorb or emit photons due to the presence of the Floquet sidebands created in the TP. The nearly perfect spin-valley-sideband filtering is predicted. Applying only the exchange field leads to just only the electron absorbing a single photon almost purely allowed to tunnel through the junction for the large electric field. Reversing direction of electric field can select spin of the allowed electron. In the case of applying only off-resonant circularly polarized light, just only the electron absorbing a single photon with spin up, is almost purely allowed to tunnel through the junction. The valley is also selected by reversing direction of the electric field. The controllable sideband channel may be applicable for sideband-based spin-valleytronics.

cond-mat.mes-hall↗

arXiv2017

Large magnetoresistance dips and perfect spin-valley filter induced by topological phase transitions in silicene

Spin-valley transport and magnetoresistance are investigated in silicene-based N/TB/N/TB/N junction where N and TB are normal silicene and topological barriers. The topological phase transitions in TB's are controlled by electric, exchange fields and circularly polarized light. As a result, we find that by applying electric and exchange fields, four groups of spin-valley currents are perfectly filtered, directly induced by topological phase transitions. Control of currents, carried by single, double and triple channels of spin-valley electrons in silicene junction, may be achievable by adjusting magnitudes of electric, exchange fields and circularly polarized light. We may identify that the key factor behind the spin-valley current filtered at the transition points may be due to zero and non-zero Chern numbers. Electrons that are allowed to transport at the transition points must obey zero-Chern number which is equivalent to zero mass and zero-Berry's curvature, while electrons with non-zero Chern number are perfectly suppressed. Very large magnetoresistance dips are found directly induced by topological phase transition points. Our study also discusses the effect of spin-valley dependent Hall conductivity at the transition points on ballistic transport and reveals the potential of silicene as a topological material for spin-valleytronics.

cond-mat.mes-hall↗

arXiv2017

Strain control of real-and lattice-spin currents in a silicene junction

We investigate real- and lattice-spin currents controlled by strain in a silicene-based junction, where chemical potential, perpendicular electric field and circularly polarized light are applied into the strained barrier. We find that the junction yields strain filtering effect with perfect strain control of real- (or lattice-) spin currents. (i) By applying electric field without circularly polarized light we show that total current is carried by pure lattice-spin up (or down) electrons tunable by strain. (ii) When circularly polarized light is irradiated onto silicene sheet without applying electric field, total current is carried by pure real-spin up (or down) electrons tunable by strain. High conductance peaks associated with pure real-(or lattice-) spin currents in case ii(or i) occur at specific magnitude of strain, yielding strain filtering effect. Magnitudes of filtered strain due to pure real- (or lattice-) spin currents may be tunable by varying chemical potential. Sensitivity may be enhanced by increasing thickness of strained barrier. Significantly, (iii) when both perpendicular electric field and circularly polarized light are applied, the total current is carried by three species of electron groups tunable by strain. This may lead to controllable numbers of electron species to transport. This result shows that strain filtering effect in a silicene-based junction is quite different from that in graphene junction. Our work reveals potential of silicene as a nano-electro-mechanical device and spin-valleytronic applications.

cond-mat.mes-hall↗

arXiv2016

Gate control of lattice-pseudospin currents in graphene on WS2: Effect of sublattice symmetry breaking and spin-orbit interaction

Strong spin-orbit interaction (SOI) in graphene grown on tungsten disulfide (WS2) has been recently observed, leading to energy gap opening by SOI. Energy gap in graphene may also be induced by sublattice symmetry breaking (SSB) where energy level in A-sublattice is not equal to that in B-sublattice. SSB-gap may be produced by growing graphene on hexagonal boron nitride or silicon carbide. In this work, we investigate transport property in a SOI/SSB/SOI gapped graphene junction, focusing the effect of interplay of SOI and SSB. We find that, lattice-pseudospin polarization (L-PSP) can be controlled perfectly from +100% to -100% by gate voltage. This is due to the fact that in graphene grown on WS2, the carriers carry lattice-pseudo spin degree of freedom "up and down". The SSB-gapped graphene exhibits pseudo-ferromagnetism to play the role of lattice-pseudospin filtering barrier. It is also found that the SOI and SSB-gaps in graphene may be measured by characteristic of L-PSP in the junction. The proposed controllable-lattice-pseudospin currents may be applicable for graphene-based pseudospintronics.

cond-mat.mes-hall↗

arXiv2015

Lattice-pseudospin and spin-valley polarizations in dual ferromagnetic-gated silicene junction

We study spin-valley and lattice-pseudo spin currents in a dual ferromagnetic-gated silicene-based junction. Silicene has buckled atomic structure which allows us to take sublattice-dependent ferromagnetism into account in the investigation. One of the study results show that transmission at the junctions exhibits anisotropic property only in anti-parallel cases. Interestingly, the studied junctions can be switched from a pure spin-polarizer to a pure valley-polarizer by reversing directions of exchange fields in the parallel junctions. The perfect control of spin-valley currents can be done only in the parallel cases and its resolution can be enhanced by increasing gate potential between the ferromagnetic barriers. The asymmetric barriers of anti-parallel junction is found to destroy both spin and valley filtering effects and yield a novel result, pure sub-lattice pseudo-spin polarization. The current in the anti-parallel junctions can be controlled to flow solely in either A or B sub-lattice, saying that the controllable lattice current in silicene is created in double ferromagnetic-gated junction. Our work reveals the potential of dual ferromagnetic-gated silicene junction which may be possible for applications in spin-valleytronics and lattice-pseudospintronics.

cond-mat.mes-hall↗

arXiv2015

Electron with arbitrary pseudo spins in multilayer graphene

Using the low-energy effective Hamiltonian of the ABC-stacked multilayer graphene, pseudo spin coupling to real orbital angular momentum of electron in multilayer graphene is investigated. We show that electron wave function in N-layer graphene mimics behavior of particle with spin of N/2. It is said that for N greater than 1 the low-energy effective Hamiltonian for ABC-stacked graphene is no longer used to describe pseudo spin 1/2-particle wave function. The wave function of electron in multilayer graphene may behave like fermionic (or bosonic) particle when N is odd (or even). This work proposes a theory of graphene as a host material of electron with arbitrary pseudo spins, tunable by changing number of graphene layers.

cond-mat.mes-hall↗

arXiv2014

Control of resonant frequency by currents in graphene: Effect of Dirac field on deflection

To construct Lagrangian based on plate theory and tight-binding model, deflection-field coupling to Dirac fermions in graphene can be investigated. As have been known, deflection-induced strain may cause an effect on the motion of the electron, like a pseudo gauge field. In the present work, we will investigate the effect of the Dirac field on the motion of the deflection-field in graphene derived from Lagrangian density. Due to the interaction of the deflection- and Dirac-fields, the current-induced surface-tension up to about N/m in graphene membrane is predicted. This result may lead to controllable resonant frequency by currents in graphene. The high resonant frequency is found to be perfectly linearly controlled by both charge and valley currents. Our work reveals the potential of graphene for application of nano-electro-mechanical device and the physics of interaction of electron and deflection-filed in graphene system is investigated.

cond-mat.mes-hall↗

arXiv2014

Pseudo spin torque induced by strain field of Dirac fermions in graphene

In contrast to recent description [Phys. Rev. Lett. 106 (2011)116803], we show that pseudo spin in graphene is not completely a real angular momentum. The pseudo spin only in the direction perpendicular to graphene sheet is real angular momentum, while the pseudo spin parallel to graphene plane is still not real angular momentum. Interestingly, it is also shown that the Newtonian-like force and pseudo spin torque of massive Dirac electrons in graphene under strain field mimic gravitomagnetic force and gravitomagnetic spin torque, respectively. This is due to the equivalence of pseudo spin and velocity operators of 2+1 dimensional massive electrons in graphene, different from that in real 3+1 dimensional Dirac fields. This work reveals new physical property of graphene as a pseudo gravitomagnetic material.

cond-mat.mes-hall↗

arXiv2011

Possible strain-induced directional superconductivity in graphene

Applying large strain in zigzag direction, gapless graphene may turns into gapped graphene at the critical strain. The energy gap between valence and conduction bands is created above the critical deformation. We theoretically predict that, using the Landauer formalism to study conductance in ballistic limit, the strain dependence of ballistic conductance, related to tight-binding-based carriers, evolves into a tremendously large conductance at the critical strain, found only for the conductance of current along armchair direction. This directional superconductance may lead graphene to resemble a superconductor. The strain-induced energy gap plays the role of the superconducting gap. This behavior is due to the fact that strain-induced change of electronic properties leads to highly anisotropic fermions to cause this tremendously large conductance.

cond-mat.mes-hall↗

arXiv2011

Tunneling conductance in strained graphene-based superconductor: Effect of asymmetric Weyl-Dirac fermions

Based on the BTK theory, we investigate the tunneling conductance in a uniaxially strained graphene-based normal metal (NG)/ barrier (I)/superconductor (SG) junctions. In the present model, we assume that depositing the conventional superconductor on the top of the uniaxially strained graphene, normal graphene may turn to superconducting graphene with the Cooper pairs formed by the asymmetric Weyl-Dirac electrons, the massless fermions with direction-dependent velocity. The highly asymmetrical velocity, vy/vx>>1, may be created by strain in the zigzag direction near the transition point between gapless and gapped graphene. In the case of the highly asymmetrical velocity, we find that the Andreev reflection strongly depends on the direction and the current perpendicular to the direction of strain can flow in the junction as if there was no barrier. Also, the current parallel to the direction of strain anomalously oscillates as a function of the gate voltage with very high frequency. Our predicted result is found as quite different from the feature of the quasiparticle tunneling in the unstrained graphene-based NG/I/SG conventional junction. This is because of the presence of the direction-dependent-velocity quasiparticles in the highly strained graphene system.

cond-mat.mes-hall↗

arXiv2010

Semi-massless fermions tunneling through a gate barrier in graphene

In the case of the strongly deformed graphene, gapless graphene may turn to gapped graphene at the critical deformation. We find that, like semi-massless fermions, electrons in the deformed graphene, at the critical point, mimic the dispersions of the massless fermions in one direction and the massive fermions in the other. Our predicted dispersion formula is the generalization of the previously predicted formula. The behavior of the particle-like semi-massless fermions tunneling through a gate barrier is contrasted with that of the (pure) massless fermions tunneling through a gate barrier in the original graphene. This is due to the effect of the combination between the massless and the massive particle dispersions at the critical deformation.

cond-mat.mes-hall↗

arXiv2010

Specular Andreev reflection of asymmetric fermions in graphene under strain

This work investigates the effect of the uniaxial strain on the tunneling conductance in a strained graphene superconductor where strain is applied in the armchair direction. Based on the Tight-Binding model, applying strain in the armchair direction gives rise to the asymmetric massless fermions as the carriers. Their velocities depend on their directions controlled by strain. Using the BTK theory, the conductances of strained graphene N/S junctions can be determined. As a result, we find that the current flowing perpendicular to the direction of strain depends linearly on strain, with the positive slope. But the current flowing parallel to the direction of strain depends linearly on strain, with the negative slope. This linear behavior is significant for applications of superconductor-based nanomechanical electronic devices.

cond-mat.supr-con↗