Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 100: Frustrated Magnets - Pyrochlore Oxides

TT 100.4: Vortrag

Donnerstag, 15. März 2018, 16:15–16:30, H 3005

Inverted hysteresis within the antiferromagnetic all-in-all-out state of the pyrochlore Nd₂Hf₂O₇ — •L. Opherden^1,2, T. Bilitewski³, J. Hornung^1,2, T. Herrmannsdörfer¹, A. Samartzis^4,5, A. T. M. N. Islam⁴, V. K. Anand⁴, B. Lake^4,5, R. Moessner³, and J. Wosnitza^1,2 — ¹Hochfeld-Magnetlabor Dresden (HLD-EMFL), HZDR, Dresden, Germany — ²Institut für Festkörper- und Materialphysik, TU Dresden, Germany — ³Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany — ⁴Abteilung Quantenphänomene in neuen Materialien, HZB, Berlin, Germany — ⁵Institut für Festkörperphysik, TU Berlin, Germany

We report the observation of an anisotropic and inverted hysteresis loop in the antiferromagnetic all-in-all-out ordered phase of Nd₂Hf₂O₇ having a negative remnant magnetization. The hysteresis emerges once exceeding a characteristic magnetic-field strength H^⋆(T) below the Neél temperature. The very unusual appearance of a negative remnant magnetization is observed for a field parallel to the [111] and [110] direction. However, for field parallel to [001] no hysteresis can be seen. For this orientation the projection of the field onto all four local spin directions is equal and, hence, both realizations of the all-in-all-out state gaining equal Zeeman energy through a canting of their spins. We show further, that the underlying all-in-all-out phase is established in Nd₂Hf₂O₇ for temperatures below T_N = 0.48 K and persists up to fields of 0.27 T. We account for the inverted hysteresis in terms of a theory of uncompensated domain-wall spins of spherical domains forming inside a fully polarized single-domain state.