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arXiv · 2009.14443

Domain Control by Adjusting Anisotropic Stress in Pyrochlore Oxide Cd2Re2O7

Satoshi Tajima·Daigorou Hirai·Yuto Kinoshita·Masashi Tokunaga·Kazuto Akiba·Tatsuo C. Kobayashi·Hishiro T. Hirose·Zenji Hiroi
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Abstract

The 5d pyrochlore oxide Cd2Re2O7 exhibits successive phase transitions from a cubic pyrochlore structure (phase I) to a tetragonal structure without inversion symmetry below Ts1 of ~200 K (phase II) and further to another noncentrosymmetric tetragonal structure below Ts2 of ~120 K (phase III). The two low-temperature phases may be characterized by odd-parity multipolar orders induced by the Fermi liquid instability of the spin-orbit-coupled metal. To control the tetragonal domains generated by the transitions and to obtain a single-domain crystal for the measurements of anisotropic properties, we prepared single crystals with the (0 0 1) surface and applied biaxial and uniaxial stresses along the plane. Polarizing optical microscopy observations revealed that inducing a small strain of approximately 0.05% could flip the twin domains ferroelastically in a reversible fashion at low temperatures, which evidences that the tetragonal deformation switches at Ts2 between c > a for phase II and c < a for phase III. Resistivity measurements using single-domain crystals under uniaxial stress showed that the anisotropy was maximum at around Ts2 and turned over across Ts2: resistivity along the c axis is larger (smaller) than that along the a axis by ~25% for phase II (III) at around Ts2. These large anisotropies probably originate from spin-dependent scattering in the spin-split Fermi surfaces of the cluster electric toroidal quadrupolar phases of Cd2Re2O7.

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Satoshi Tajima, Daigorou Hirai, Yuto Kinoshita, Masashi Tokunaga, Kazuto Akiba, Tatsuo C. Kobayashi, Hishiro T. Hirose, Zenji Hiroi. 2020-09-30. Domain Control by Adjusting Anisotropic Stress in Pyrochlore Oxide Cd2Re2O7. https://doi.org/10.7566/jpsj.89.114711

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