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$_2$
| Autor: | Surmach, M. A., Deng, B. J. Chen Z., Jin, C. Q., Glasbrenner, J. K., Mazin, I. I., Ivanov, A., Inosov, D. S. |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 97, 104418 (2018) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.97.104418 |
| Popis: | 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, $T_{\mathrm{C}}$, 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 $T_{\mathrm{C}}$. 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. Comment: 6 pages, 4 figures |
| Databáze: | arXiv |
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