Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 46: Poster Session: Frustrated Magnets, Quantum Magnets, Charge Order and Complex Oxids

TT 46.8: Poster

Wednesday, March 18, 2020, 15:00–19:00, P2/2OG

Investigation of the thermodynamic effects of electron-nucleus interactions in pyrochlores — •J. Gronemann^1,2, T. Gottschall¹, C. Salazar¹, J. Hornung¹, T. Herrmannsdörfer¹, A. Islam³, V. Anand³, B. Lake^3,4, H. Kaneko⁵, H. Suzuki⁶, and J. Wosnitza^1,2 — ¹HLD-EMFL, HZDR, Dresden, Germany — ²Inst. f. Festkörper- und Materialphysik, TU Dresden, Germany — ³Helmholtz-Zentrum Berlin, Germany — ⁴Inst. f. Festkörperphysik, TU Berlin, Germany — ⁵Dep. of Quantum Matter, Hiroshima Univ., Japan — ⁶Dep. of Physics, Kanazawa Univ., Japan

We have investigated selected pyrochlore compounds in order to study possible nuclear magnetic contributions to the formation of their magnetic ground states and unconventional excitations. For that we focused on Ho₂Ti₂O₇ and Pr₂Hf₂O₇. Both are representatives for the occurence of spin-ice behavior.¹⁶⁵Ho and ¹⁴¹Pr are isotopically pure elements and have large hyperfine enhanced nuclear magnetic moments. The non-spherical ¹⁶⁵Ho nuclei, in addition, carry large electric quadrupole moments. For this reason, these two pyrochlore compounds are well suited to determine possible nuclear magnetic influence. Our specific heat and ac susceptibility data measured at 0.06 K to 10 K suggest a formation of a complex F^→ = J^→ + I^→ coupled ground state which is further modified by electrical field gradients. The ground state F multiplets of Ho₂Ti₂O₇ and Pr₂Hf₂O₇, in consequence, are accompanied by a total entropy which is significantly larger than the one of a purely electronic CEF ground state doublet and in particular larger than the Pauling residual entropy.