Pressure effect on the magnetism of the diluted magnetic semiconductor ( B a 1 − x K x ) ( Z n 1 − y M n y ) 2 A s 2 with independent spin and charge doping

We used x-ray magnetic circular dichroism (XMCD) to probe the ferromagnetic properties of As $p$-symmetric ($4p$) states in the recently synthesized diluted magnetic semiconductor $(\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}{\mathrm{K}}_{x}){(\mathrm{Z}{\mathrm{n}}_{1\ensuremath{-}y}\mathrm{M}{\mathrm{n}}_{y})}_{2}\mathrm{A}{\mathrm{s}}_{2}$ system under ambient- and high-pressure conditions. The As $K$-edge XMCD signal scales with the sample magnetization (dominated by Mn) and scales with the ferromagnetic ordering temperature $T\mathrm{c}$, and hence it is representative of the bulk magnetization. The XMCD intensity gradually decreases upon compression and vanishes at around 25 GPa, indicating quenching of ferromagnetism at this pressure. Transport measurements show a concomitant increase in conductivity with pressure, leading to a nearly metallic state at about the same pressure where magnetic order collapses. High-pressure x-ray diffraction shows an absence of structural transitions to 40 GPa. The results indicate that the mobility of doped holes, probed by both transport and x-ray absorption spectroscopy ($4p$ band broadening), is intimately connected with the mechanism of magnetic ordering in this class of compounds and that its control using external pressure provides an alternative route for tuning the magnetic properties in diluted magnetic semiconductor materials.