Entropy production by thermodynamic currents in ambipolar conductors with identical spin dynamics characteristics between holes and electrons

Abstract

We have evaluated the role of spin current in the energy dissipation mechanism in ambipolar conductors with identical spin-related characteristics between holes and electrons. Application of the Gibbs–Duhem relation to ambipolar conductors establishes a thermodynamic relation between the spin-dependent chemical potentials of holes and electrons, inducing an asymmetric spin splitting between the hole and electron chemical potentials. This yields two types of spin relaxation so as to allow the antiparallel spin current, where hole and electron spins flow in the opposite direction, to have a large spin diffusion length, but to retain that of the parallel spin current at a standard value.

Spatiotemporal characteristics of spin transport in compensated metals with electron–hole exchange interaction

“…As with the nonmagnetic case, two types of spin transport modes appear, both involving coupled electron and hole spin densities, as indicated by (C.4) and (C.6) of the appendix. We now compare the present study with a preceding study [8], which did not use any specific electron-hole interaction but instead made the following assumptions: (i) identical electron and hole spin relaxation times, τ (e) ↑↓ = τ (h) ↑↓ (≡ τ ↑↓ ), τ (e) ↓↑ = τ (h) ↓↑ (≡ τ ↓↑ ); (ii) identical spin polarization P (h) s = P (e) s under spin accumulation, where P (e) s and P (h) s are the electron and hole spin polarizations, respectively; and (iii) an ad hoc use of the Gibbs-Duhem relation yielding (1…”

“…↓ [8]. The antiparallel spin current contributes to a self-sustained resonance mechanism of the Hall effect [45].…”

“…These studies stimulate us to implement spin dependent electron-hole interaction into individual electron and hole spin transports. This problem has not been tackled so far, though a thermodynamical consideration based on the Gibbs-Duhem relation was reported [8].…”

Spin-charge-coupled transverse resistance in an ambipolar conductor YH2-based Hall-bar structure with perpendicularly magnetized current-injection electrodes

“…The metal exhibited a hysteresis-loop feature in the Hall voltage when a perpendicularly magnetized Tb 0.26 Fe 0.66 Co 0.08 electrode was utilized as both the current injection and voltage detection electrodes [26]. To investigate the large spin-diffusion length in Bi 1−x Pb x and YH 2 , a thermodynamic model considering the Gibbs-Duhem relation and a microscopic model based on the Baber collision with spin-flipping have been proposed [27,28], although direct experimental verification has not been conducted. Metallic systems having both electron-like and hole-like Fermi surfaces have received renewed interest in recent years because the studies on electron-hole compensation largely overlap or closely correlate with those on emerging materials such as topological systems where the carrier spin and momentum are locked.…”