Tohoku University · Engineering
Professor Ping Tang's research lab specializes in theoretical and computational condensed matter physics, with a focus on quantum materials and their emergent phenomena. Key research directions include the electronic and magnetic properties of battery materials—particularly olivine and other polymorphs of FePO₄ and LiFePO₄—ferroelectrics with novel quasiparticles like 'ferrons,' and spin transport in quantum materials such as antiferromagnets and systems exhibiting the orbital Hall effect. The lab employs advanced first-principles methods, including density functional theory and quantum transport theories, to explore phenomena ranging from multiferroicity and electric switching to spin pumping and thermoelectric responses in low-dimensional and van der Waals heterostructures.
Figures are computed from collected data and may differ slightly.
The electronic structures of ${\mathrm{FePO}}_{4}$ and $\mathrm{Li}M{\mathrm{PO}}_{4},$ where $M=\mathrm{Mn},$ Fe, Co, and Ni, are studied within the framework of density-functional theory. These materials have interesting magnetic properties and have promising technological interest as cathode materials in rechargeable batteries. A comparison of results for various spin configurations suggests that the ferromagnetic configuration, while not seen experimentally, can serve as a useful approximati
We address the sliding thermodynamics of van der Waals-bonded bilayers by continuum electromechanics. We attribute the robustness of the ferroelectricity recently observed in h-BN and WTe_{2} bilayers to large in-plane stiffness of the monolayers. We compute the electric susceptibility and specific heat in a mean-field self-consistent phonon approximation. We compare critical temperatures and electric switching fields with the observed values.
We identify the bosonic excitations in ferroelectrics that carry electric dipoles from the phenomenological Landau-Ginzburg-Devonshire theory. The ``ferron'' quasiparticles emerge from the concerted action of anharmonicity and broken inversion symmetry. In contrast to magnons, the transverse excitations of the magnetic order, the ferrons in displacive ferroelectrics are longitudinal with respect to the ferroelectric order. Based on the ferron spectrum, we predict temperature-dependent pyroelectr
The orbital Hall effect (OHE) has garnered much attention as a promising approach to realize highly efficient "orbitronic" devices with a wide range of materials. However, the existing theories that attempt to explain the experimental evidence focus on the intrinsic effect, neglecting the omnipresent disorder. Here, we formulate the impact of random defect scattering on the orbital Hall effect by a quantum Boltzmann equation and solve it for a generic two-band model including the in-scattering c
Antiferromagnets attract much interest because of their potential for spintronic applications and open fundamental physics questions, but especially noncollinear antiferromagnets remain relatively unexplored. Here, we formulate the thermal and coherent pumping of spins in noncollinear antiferromagnets|normal metal bilayers. We find that the spin current polarization is a vector with components along both the Néel vector and net magnetic moment. The spin mixing conductance for the coherent spin p
$\mathrm{Li}\mathrm{Fe}\mathrm{P}{\mathrm{O}}_{4}$ in the olivine structure is a promising cathode material for Li ion batteries. During normal battery operation, an olivine form of $\mathrm{Fe}\mathrm{P}{\mathrm{O}}_{4}$ is produced. In addition to the olivine form, $\mathrm{Fe}\mathrm{P}{\mathrm{O}}_{4}$ is known to form in a quartzlike structure, a high pressure $\mathrm{Cr}\mathrm{V}{\mathrm{O}}_{4}$-like structure, and a monoclinic structure. We report the results of a detailed density func
Aluminum antimony (AlSb) is a promising photovoltaic material with a band gap of about 1.62 eV. However, AlSb is highly deliquescent and not stable, which has brought great difficulties to the applications. Based on the above situation, there are two purposes for preparing our Zn-doped AlSb (AlSb:Zn) thin films: One is to make P-type AlSb and the other is to find a way to suppress the deliquescence of AlSb. The AlSb:Zn thin films were prepared on glass substrates at different substrate temperatu
We predict a magnonic resonant tunneling phenomenon in the double-barrier insulating magnon junctions of ${\text{FI}}_{1}/{\text{AFI}}_{1}/{\text{FI}}_{2}/{\text{AFI}}_{2}/{\text{FI}}_{3}$, where ${\text{FI}}_{(1,2,3)}$ and ${\text{AFI}}_{(1,2)}$ denote the ferromagnetic and antiferromagnetic insulating layers, respectively. Similar to electron tunneling in well-known double-barrier magnetic tunnel junctions, each antiferromagnetic insulator layer acts as an effective potential barrier for magno
Duct-vented gas explosion was simulated based on k-ɛ turbulence model and Eddy-Dissipation-Concept (EDC) model in this paper. Flame propagation process during venting was studied to analyze the mechanisms of the severer explosion severity compared with direct venting. Effect of vent duct quantity was also studied. It is shown that explosion in duct leads to the higher maximum reduced pressure (Pred); frictional drag and gas column inertia play minor roles in intensifying explosion violence; use
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