# Tunable Magnetic Transition to a Singlet Ground State in a 2D Van der Waals Layered Trimerized Kagom\'e Magnet

## TL;DR

This study reveals a tunable magnetic phase transition in 2D Nb3X8 (X=Cl, Br) layered kagomé magnets, where a structural rearrangement induces a switch from paramagnetic to singlet ground state, with potential applications in electronic and magnetic devices.

## Contribution

It demonstrates a systematic control of magnetic transition temperature and phase behavior in a family of 2D layered kagomé magnets through chemical substitution and structural analysis.

## Key findings

- Magnetic transition from paramagnetic to singlet state observed.
- Structural rearrangement accompanies magnetic phase change.
- Transition temperature tunable near room temperature.

## Abstract

Incorporating magnetism into two dimensional (2D) van der Waals (VdW) heterostrutures is crucial for the development of functional electronic and magnetic devices. Here we show that Nb3X8 (X = Cl, Br) is a family of 2D layered trimerized kagom\'e magnets that are paramagnetic at high temperatures and undergo a first order phase transition on cooling to a singlet magnetic state. X-ray diffraction shows that a rearrangement of the VdW stacking accompanies the magnetic transition, with high and low temperature phases consistent with STEM images of the end members {\alpha}-Nb3Cl8 and \b{eta}-Nb3Br8. The temperature of this transition is systematically varied across the solid solution Nb3Cl8-xBrx (x = 0-8), with x = 6 having transitions near room temperature. The solid solution also varies the optical properties, which are further modulated by the phase transition. As such, they provide a platform on which to understand and exploit the interplay between dimensionality, magnetism, and optoelectronic behavior in VdW materials.

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Source: https://tomesphere.com/paper/1907.10108