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Possible quadrupole-order-driven commensurate-incommensurate phase transition in B20 CoGe

Abstract

The B20-type cobalt germanide CoGe was investigated by measuring the specific heat, resistivity, and 59Co nuclear magnetic resonance (NMR).We observed a phase transition at TQ = 13.7 K, evidenced by a very narrow peak of the specific heat and sharp changes of the nuclear spin-spin (T −1 2 ) and spin-lattice (T −1 1 ) relaxation rates. The fact that the entropy release is extremely small and the Knight shift is almost independent of temperature down to low temperatures as anticipated in a paramagnetic metal indicates that the TQ transition is of nonmagnetic origin. In addition, we detected a crossover scale T0 ∼ 30 K below which the resistivity and the NMR linewidth increase, and T −1 1 is progressively distributed in space, that is, a static and dynamical spatial inhomogeneity develops. While the order parameter for the TQ transition remains an open question, a group-theoretical analysis suggests that the finite electric quadrupole density arising from the low local site symmetry at cobalt sites could drive the crystal symmetry lowering from the P213 symmetry that is commensurate to the R3 symmetry with an incommensurate wave vector, which fairly well accounts for the TQ transition. The quadrupole-order-driven commensurate-incommensurate phase transition may be another remarkable phenomenon arising from the structural chirality inherent in the noncentrosymmetric B20 family.

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Category:
Articles
Type:
artykuły w czasopismach
Published in:
PHYSICAL REVIEW B no. 105,
ISSN: 2469-9950
Language:
English
Publication year:
2022
Bibliographic description:
Baek S., Sidorov V., Nikolaev A. V., Klimczuk T., Ronning F., Tsvyashchenko A. V.: Possible quadrupole-order-driven commensurate-incommensurate phase transition in B20 CoGe// PHYSICAL REVIEW B -Vol. 105,iss. 16 (2022),
DOI:
Digital Object Identifier (open in new tab) 10.1103/physrevb.105.165132
Sources of funding:
  • COST_FREE
Verified by:
Gdańsk University of Technology

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