# Selective generation and amplification of RKKY interactions by P-N interface

## TL;DR

This paper introduces a mechanism to control and amplify anisotropic RKKY interactions between local spins using P-N interfaces and spin-orbit coupling on topological insulators, with potential applications in quantum computing.

## Contribution

It presents a novel method to selectively generate and enhance RKKY interactions via P-N interfaces, enabling independent control of interaction strength and anisotropy.

## Key findings

- Analytical and numerical demonstration of the mechanism.
- P-N interface as a control knob for RKKY interactions.
- Potential applications in quantum computation and criticality.

## Abstract

We propose a physical mechanism to generate and selectively amplify anisotropic Rudermann-Kittel-Kasuya-Yosida (RKKY) interactions between two local spins. The idea is to combine the deflection of the carrier velocity by a P-N interface and the locking of this velocity to the carrier spin orientation via spin-orbit coupling. We provide analytical and numerical results to demonstrate this mechanism on the surface of a topological insulator P-N junction. This work identifies the P-N interface as a second knob which, together with the carrier density, enables independent control of the strength and anisotropy of the RKKY interaction over a wide range. These findings may be relevant to scalable quantum computation and two-impurity quantum criticality.