arXiv subjects

Xing-Jian Yi

Publications and source records attributed to Xing-Jian Yi.

3 recordsLinked to original sources

arXiv2026

Majorana modes in helical altermagnet without net magnetism and spin-orbit coupling

We propose a scheme to realize topological superconductor and Majorana bound states (MBSs) in a one-dimensional metal nanowire on the surface of a helical altermagnet and in proximity to an s-wave superconductor, removing the requirement of conventional spin-orbit coupling and net magnetism. Through gauge transformation, we demonstrate that the helical frame naturally induces spin-momentum locking while the altermagnetism breaks time-reversal symmetry. The topological superconducting phase is well tuned by chemical potential, altermagnet strength, and helical frequency. Besides, our transport calculation results reveal quantized conductance signatures: a 2e2/h zero-bias peak at nanowire ends and a 4e2/h tunneling conductance at the domain wall of nanowires with opposite chirality, detected via metal lead and scanning tunneling microscopy, respectively. Our research offers new perspectives on finding MBSs.

cond-mat.supr-con↗

arXiv2026

Spin transport in a normal meta-altermagnetic superconducting nanowire junction

Spin triplet superconductors are considered a promising platform for dissipationless spin transport, where spin currents are carried by spin triplet Cooper pairs. In this paper, we propose that the spin triplet superconductivity and spin supercurrent can be engineered in an altermagnetic superconducting nanowire, where a one-dimensional nanowire is placed on the surface of an s-wave superconductor and in proximity to the altermagnet. Using the nonequilibrium Green's function method, we demonstrate a nonzero equal spin Andreev reflection coefficient at the normal metal-altermagnetic superconducting nanowire interface, thereby verifying the injection of spin triplet Cooper pairs. Furthermore, we systematically investigate the spin transport properties in this hybrid system under a spin bias. Our results demonstrate that these properties can be effectively tuned by the chemical potential and spin bias orientation. Our proposal provides a pathway toward realizing dissipationless spin transport.

cond-mat.supr-con↗

arXiv2025

Spin Splitting Nernst Effect in Altermagnet

Altermagnet is a distinctive magnet phase, which has spin-split energy band but with zero net magnetic moment. In this paper, we propose that altermagnet behaves spin splitting Nernst effect: Under a longitudinal temperature gradient, the electrons with opposite spins tend to split oppositely in the transverse direction, thus generating a transverse spin current. The spin splitting Nernst effect is understood from the contribution of the longitudinal wave vector to the transverse group velocity. Using the nonequilibrium Green's function method, we calculate the spin-dependent transmission coefficient in the four-terminal altermagnet device. From the spin-dependent transmission coefficient, the nonzero transverse spin current from longitudinal temperature gradient is obtained, and the spin splitting Nernst effect is verified. We systematically study the parameter dependence of the spin splitting Nernst effect, while also performing symmetry analysis. The spin splitting Nernst effect can be easily regulated by Fermi surface energy, temperature, transport direction, and system size. Furthermore, in altermagnet, the $xy$-response and $yx$-response spin splitting Nernst coefficients are equal with $N_{s,xy}=N_{s,yx}$, different from the conventional spin Nernst effect where they are opposite. Meanwhile, the spin splitting Nernst effect require neither spin-orbit coupling nor net magnetism.

cond-mat.mes-hall↗