# Giant negative magnetoresistance and kinetic arrest of first-order ferrimagnetic-antiferomagnetic transition in Ge doped Mn$_2$Sb

## TL;DR

This study investigates how germanium doping in Mn₂Sb influences its magnetic phase transition, revealing giant negative magnetoresistance and kinetic arrest phenomena in the ferrimagnetic-antiferromagnetic transition.

## Contribution

It demonstrates that Ge substitution can tune the transition temperature and induce kinetic arrest, leading to giant negative magnetoresistance in Mn₂Sb.

## Key findings

- Transition temperature (Tt) can be tuned between 119 K and 271 K.
- Giant negative magnetoresistance of up to 70%.
- Kinetic arrest of the FRI-AFM transition observed with Ge doping.

## Abstract

Effect of Ge substitution on first order ferrimagnetic (FRI) - antiferromagnetic (AFM) transition in Mn$_2$Sb has been studied. It shows that transition temperature (T$_t$) can be tuned between 119~K - 271~K by substituting 2.5-10\% Ge at Sb site in Mn$_2$Sb. The variation of density of state at Fermi level N(E$_f$) with Ge substitution shows that dN(E)/dE is positive at E$_f$ in the AFM state. With the application of magnetic field T$_t$ shifts to low temperature, which results in a giant negative magnetoresistance (MR) reaching a value of 70\% for 2.5\% substitution. Our results show that FRI to AFM transformation during cooling stops around 35 K, even though it remains incomplete. It along with non-monotonic variation of lower critical field, open loop in isothermal MR and increasing difference in zero field cooled warming (ZFCW) and field cooled warming (FCW) resistivity with increasing magnetic field shows that FRI to AFM transition is kinetically arrested in the case of 2.5\% Ge substitution.