# High-performance nanoscale topological energy transduction

## TL;DR

This paper introduces a new on-chip inductor design using ferromagnetic islands on topological insulators, achieving high inductance densities at terahertz frequencies through topological effects and advanced simulations.

## Contribution

It presents a novel magnetic energy transduction method leveraging topological insulators and ferromagnetic islands, enabling high-performance inductors with compact size and high-frequency operation.

## Key findings

- Achieves inductance densities up to terahertz frequencies.
- Utilizes topological surface states for magnetic flux concentration.
- Demonstrates the effectiveness of the novel inductor design through simulations.

## Abstract

The realization of high-performance, small-footprint, on-chip inductors remains a challenge in radio-frequency and power microelectronics, where they perform vital energy transduction in filters and power converters. Modern planar inductors consist of metallic spirals that consume significant chip area, resulting in low inductance densities. We present a novel method for magnetic energy transduction that utilizes ferromagnetic islands (FIs) on the surface of a 3D time-reversal-invariant topological insulator (TI) to produce paradigmatically different inductors. Depending on the chemical potential, the FIs induce either an anomalous or quantum anomalous Hall effect in the topological surface states. These Hall effects direct current around the FIs, concentrating magnetic flux and producing a highly inductive device. Using a novel self-consistent simulation that couples AC non-equilibrium Green functions to fully electrodynamic solutions of Maxwell's equations, we demonstrate excellent inductance densities up to terahertz frequencies, thus harnessing the unique properties of topological materials for practical device applications.