Step conductance and spin selectivity in a one dimensional tailored conical magnet

TL;DR

We analyze a one-dimensional free-electron gas coupled via double exchange to a classical conical magnet within a coherent transport framework. Using a multi-channel S-matrix (Landauer-Büttiker) approach, we demonstrate that the conductance G exhibits integer steps within distinct energy windows, corresponding to potential and diffractive scattering regimes. By exploring conical magnets with varying axis orientation and profile—including a chiral soliton lattice—we provide a unified, spin-selective interpretation grounded in the electron spin alignment with the conical axis and the chirality of the magnetic field. The results offer a concrete mechanism for chiral-induced spin selectivity (CISS) in 1D systems and point to experimental platforms using tailored chiral magnets to observe stepwise conductance and spin filtering at accessible energy scales, with robust behavior against moderate disorder.

Abstract

Using an S-matrix formulation we evaluate the conductance of a one dimensional free electron gas in double exchange interaction with a classical conical magnet. We find integer conductance steps depending on the energy window of the incoming electrons for conical magnets described by a fictitious magnetic field of different orientations and modulated profile. The conductance windows, that we attribute to potential or diffractive scattering, are characterised by spin selectivity depending on the fictitious magnetic field direction and chirality. Furthermore, we study the conductance of a conical soliton lattice and discuss a rationalization of all the conductance data for an incoming electron with arbitrary spin direction in terms of scattering of an electron with spin along the conical axis.

Figures (10)

• Figure 1: ${\hat{y}}$ - conical magnet.
• Figure 2: Conductance as a function of energy of a spiral magnet rotating around the ${\hat{y}}$-axis, (a) ${\vec{h}}(y)=h(\cos Qy,0,\sin Qy)$, (b) ${\vec{h}}(y)=h\sin(\pi x/L)(\cos Qy,0,\sin Qy)$, $\epsilon_{\pm}=(Q/2)^2\pm h$ (red).
• Figure 3: Spectrum of the ${\hat{y}}$ - conical magnet, (a) $\theta=0$, $\epsilon_{\pm}= (Q/2)^2\pm h$ (cyan), $\epsilon_-(q)$ (blue), $\epsilon_+(q)$ (red), ${\bar{\epsilon}}_-(iq)$ (black), ${\bar{\epsilon}}_+(iq)$ (green), (b) $\theta=\pi/3$, $\epsilon_0=h\sin \theta$, $\epsilon_{\pm}= (Q/2)^2\pm h\cos \theta$ (cyan).
• Figure 4: Conductance as a function of energy of a modulated ${\hat{y}}$-conical magnet $(\theta=\pi/3)$, $\epsilon_{\pm}= (Q/2)^2\pm h\cos\theta,~ \epsilon_0=h\sin \theta$.
• Figure 5: $\hat{z}$ - conical magnet.