A substantial increase of Curie temperature in a new type of diluted magnetic semiconductors via effects of chemical pressure

TL;DR

This study demonstrates that applying chemical pressure through Ca substitution in a new diluted magnetic semiconductor significantly increases its Curie temperature and magnetic properties, offering a promising route to enhance magnetic performance.

Contribution

The paper introduces a novel chemical pressure approach to substantially increase the Curie temperature in a new class of diluted magnetic semiconductors.

Findings

Curie temperature increased by about 50%.

Saturation magnetic moment more than doubled.

Chemical pressure equivalent to 3.6 GPa external pressure.

Abstract

Chemical pressure is an effective method to tune physical properties, particularly for diluted magnetic semiconductors (DMS) of which ferromagnetic ordering is mediated by charge carriers. Via substitution of smaller Ca for larger Sr, we introduce chemical pressure on (Sr,Na)(Cd,Mn)2As2 to fabricate a new DMS material (Ca,Na)(Cd,Mn)2As2. Carriers and spins are introduced by substitutions of (Ca,Na) and (Cd,Mn) respectively. The unit cell volume reduces by 6.2% after complete substitution of Ca for Sr, suggesting a subsistent chemical pressure. Importantly the local geometry of [Cd/MnAs4] tetrahedron is optimized via chemical compression that increases the Mn-As hybridization leading to enhanced ferromagnetic interactions. As a result, the maximum Curie temperature (TC) is increased by about 50% while the the maximum saturation moment increases by over 100% from (Sr,Na)(Cd,Mn)2As2 to (Ca,Na)(Cd,Mn)2As2. The chemical pressure estimated from the equation of state is equal to an external physical pressure of 3.6 GPa.