Time reversal reserved spin valve and spin transistor based on unconventional $p$-wave magnets

Abstract

The anisotropic spin splitting in unconventional magnets opens new opportunities for realizing spintronic functionalities without relying on net magnetization or relativistic spin-orbit coupling. Here, we propose a spin valve and a spin transistor based on unconventional $p$-wave magnets (UPMs). The spin valve is realized in a junction where a normal metal is sandwiched between two UPMs whose exchange-field strength vectors are oriented transverse to the junction direction. The conductance of such a device is governed by the spin alignment between two UPMs: when their strength vectors are parallel, the spin-state alignment enables efficient electron transmission, leading to a high-conductance state; in contrast, the antiparallel configuration suppresses the conductance owing to the opposite spin orientations. Furthermore, the spin-valve can be extended to a spin transistor by replacing the central normal metal with another UPM with a longitudinally oriented strength vector and a perpendicular spin polarization axis. The central UPM enables uniform spin precession with the same precession frequency for all transverse modes. Both devices can be electrically controlled by modulating the strength vectors of UPMs. These findings establish UPMs as a promising platform for developing spintronic devices without net magnetization or relativistic spin-orbit coupling.

Figures (4)

• Figure 1: Schematic of a UPM/UPM/UPM junction. In the left and right leads, the strength vectors of two UPMs are along the $y$ direction, inducing a splitting of the Fermi surface along the $k_y$ direction. And the spin polarization is along the $z$ direction. In the central UPM, the strength vector is along the $x$ direction and the spin polarization is along the $x$ direction, enabling a spin precession.
• Figure 2: (a) and (b): Spin-split Fermi circles in two leads for the antiparallel configuration at negative and positive Fermi energies, respectively. (c): The conductance as the function of the Fermi energy of the UPM-based spin valve in the parallel and antiparallel configurations. The parameters used are as follows: $\alpha_{yL}=0.5$, $\alpha_{yR}=-\alpha_{yL}$, $\alpha_y=|\alpha_{yL}|=|\alpha_{yR}|$, $U_0 = -2t_0$, $L_x = 100a$, with $a=1$ the lattice constant and $t_0=1$ the energy unit.
• Figure 3: Spin-split subbands in the three regions of the UPM-based SFET in the antiparallel configuration of two leads. Panels (a)--(c), (d)--(f), and (g)--(i) correspond to $k_y = 0.1\pi/a$, $k_y = 0$, and $k_y = -0.1\pi/a$, respectively. Different colors correspond to distinct spin orientations. The parameters used are as follows: $U_0 = -2t_0$, $t_{yL} = 0.5t_0$, $t_{yR} = -0.5t_0$, $t_x = 0.2t_0$.
• Figure 4: Conductance oscillations versus $t_x$ and $L_x$ at negative Fermi energies in the SFET. Parameters for (b) and (e): $E_F = -0.1t_0$; for (c) and (f): $E_F = -0.1t_0$, $L_x = 100a$, $t_x = 0.1t_0$; for all: $U_0 = -2t_0$.