Crystals, magnetic and electronic properties of a new ThCr2Si2-type BaMn2Bi2 and K-doped compositions

TL;DR

This paper reports the synthesis and characterization of a new ThCr2Si2-type BaMn2Bi2 compound and its K-doped variants, revealing their magnetic, electronic, and structural properties, including antiferromagnetism and doping-induced metallicity.

Contribution

It introduces new BaMn2Bi2-based materials with detailed structural, magnetic, and electronic property analysis, including effects of potassium doping.

Findings

BaMn2Bi2 is antiferromagnetic with a band gap of 6 meV.

Potassium doping induces metallic behavior in BaMn2Bi2.

Doped samples show enhanced magnetic anisotropy and complex low-temperature behavior.

Abstract

This is a report on the new 122 ternary transition-metal pnictide of BaMn2Bi2, which is crystallized from bismuth flux. BaMn2Bi2 adopts ThCr2Si2-type structure (I4/mmm) with a = 4.4902(3) {\AA} and c = 14.687(1) {\AA}; it is antiferromagnetic with anisotropic magnetic susceptibility and semiconducting with a band gap of Eg = 6 meV. Heat capacity result confirms the insulating ground state in BaMn2Bi2 with the electronic residual Sommerfeld coefficient of {\gamma} ~ 0. The high temperature magnetization results show that magnetic ordering temperature is TN ~ 400 K. Hole-doping in BaMn2Bi2 via potassium in Ba1-xKxMn2Bi2 results in metallic behavior for x = 0.10(1), 0.32(1) and 0.36(1). With K-doping, more magnetically anisotropic behavior is observed. Although there is a downturn in electrical resistivity and low-field magnetization data below 4 K in > 30%-doped crystals, there is no sign of zero resistance or diamagnetism. This manuscript is a report on new materials of BaMn2Bi2 and Ba1-xKxMn2Bi2 (0 < x < 0.4). Results from powder X-ray diffraction, anisotropic temperature- and field-dependent magnetization, temperature-and field-dependent electrical resistivity, and heat capacity are presented.