Defect Controlled Ferromagnetic Ordering in Au Implanted TiSe$_2$ Nanocrystals

TL;DR

This study demonstrates how Au ion implantation in Se-deficient TiSe2 nanocrystals induces and controls ferromagnetic ordering, revealing tunable magnetic properties relevant for spintronics and sensing technologies.

Contribution

It introduces a novel method of tuning ferromagnetism in TiSe2 via Au ion implantation, linking defect engineering with magnetic property control in 2D materials.

Findings

Au implantation induces ferromagnetism in TiSe2.

Magnetization can be tuned by ion fluence and nanoparticle size.

Faster saturation of magnetization at lower fields in implanted samples.

Abstract

Layered transition metal dichalcogenides (TMDs) are attracting increasing attention because they exhibit unconventional magnetic properties due to crystal imperfections in their usually non-magnetic 2D structure. This work aims to investigate the magnetic response of self-engineered Se deficient TiSe$_2$ thin films, synthesized using chemical vapour deposition. We demonstrate tunability of the ferromagnetic order with the introduction of Au atoms using low energy Au ion implantation, which works as a controlling knob to vary the stoichiometry of Se in TiSe$_{2-x}$. The corresponding isothermal field-magnetization curves fit well with a modified Brillouin J function with J value of 1.5 for Ti$^{3+}$, and 4 for Au$^{3+}$, accounting for the diamagnetism that arises from Au implantation. We propose a qualitative model for the experimentally observed magnetization as a function of ion fluence, corroborated with high-resolution transmission electron microscopy. Depending on the Au nanoparticle size in the implanted samples, magnetization saturates faster at a much lower applied magnetic field than the pristine sample. Our findings hold potential to expand the range of 2D ferromagnetic materials for spintronics and magnetic sensing applications.