Weak doping dependence of the antiferromagnetic coupling between nearest-neighbor Mn$^{2+}$ spins in (Ba$_{1-x}$K$_x$)(Zn$_{1-y}$Mn$_y$)$_2$As$_2$

M. A. Surmach; B. J. Chen Z. Deng; C. Q. Jin; J. K. Glasbrenner; I. I. Mazin; A. Ivanov; D. S. Inosov

doi:10.1103/PhysRevB.97.104418

paper

Weak doping dependence of the antiferromagnetic coupling between nearest-neighbor Mn $^{2 +}$ spins in (Ba $_{1 - x}$ K $_{x}$ )(Zn $_{1 - y}$ Mn $_{y}$ ) $_{2}$ As $_{2}$

arXiv:1802.02847 · doi:10.1103/PhysRevB.97.104418

Abstract

Dilute magnetic semiconductors (DMS) are nonmagnetic semiconductors doped with magnetic transition metals. The recently discovered DMS material (Ba $_{1 - x}$ K $_{x}$ )(Zn $_{1 - y}$ Mn $_{y}$ ) $_{2}$ As $_{2}$ offers a unique and versatile control of the Curie temperature, $T_{C}$ , by decoupling the spin (Mn $^{2 +}$ , $S = 5/2$ ) and charge (K $^{+}$ ) doping in different crystallographic layers. In an attempt to describe from first-principles calculations the role of hole doping in stabilizing ferromagnetic order, it was recently suggested that the antiferromagnetic exchange coupling $J$ between the nearest-neighbor Mn ions would experience a nearly twofold suppression upon doping 20\% of holes by potassium substitution. At the same time, further-neighbor interactions become increasingly ferromagnetic upon doping, leading to a rapid increase of $T_{C}$ . Using inelastic neutron scattering, we have observed a localized magnetic excitation at about 13 meV, associated with the destruction of the nearest-neighbor Mn-Mn singlet ground state. Hole doping results in a notable broadening of this peak, evidencing significant particle-hole damping, but with only a minor change in the peak position. We argue that this unexpected result can be explained by a combined effect of superexchange and double-exchange interactions.

6 pages, 4 figures

Weak doping dependence of the antiferromagnetic coupling between nearest-neighbor Mn2+ spins in (Ba1−x​Kx​)(Zn1−y​Mny​)2​As2​

Abstract

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Weak doping dependence of the antiferromagnetic coupling between nearest-neighbor Mn $^{2 +}$ spins in (Ba $_{1 - x}$ K $_{x}$ )(Zn $_{1 - y}$ Mn $_{y}$ ) $_{2}$ As $_{2}$