Magnetic field-Temperature Phase Diagram of CeCoSi Constructed by Specific Heat, Magnetoresistivity, and Magnetization Measurements for a Single Crystal

Hidaka, Hisao; Yanagiya, Shun; Hayasaka, Eikai; Kaneko, Yuma; Yanagisawa, Tatsuya; Tanida, Hiroshi; Arima, Hiroshi

doi:10.48550/arxiv.2203.09754

Cited by 1 publication

(1 citation statement)

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“…[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] CeCoSi is one of the potential candidates with AFQ orderings in the tetragonal crystal structure, where the CEF levels consist of only the Kramers pairs. [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] This material shows the signature of two ordered phases including a higherrank multipolar ordered phase, which is denoted as II and III phases in addition to a high-temperature paramagnetic phase (I phase); the low-temperature III phase was indicated to be characterized by an in-plane antiferromagnetic (AFM) spin configuration with ordering vector q = 0 and the II phase was suggested to be an AFQ phase, 60-62, 64, 70) although the order parameter of the II phase has not been identified yet. Since the q = 0 order described by the staggered-type alignment of the order parameters on two Ce ions [Ce (A) and Ce (B) in Fig.…”

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confidence: 99%

Mean-field Study of Antiferromagnetic and Antiferroquadrupolar Orderings in Tetragonal CeCoSi

Yatsushiro,

Hayami

2022

Preprint

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We investigate the stability of the multipolar orderings in f -electron material CeCoSi based on a self-consistent meanfield calculation for the effective localized model. This material has two ordered phases in the temperature-pressure phase diagram: the antiferromagnetic phase and the nonmagnetic phase, the latter of which has been suggested to be an antiferroquadrupolar phase. Meanwhile, the origin of the antiferroquadrupolar phase has been unclear, since a quadrupole degree of freedom is present only between the ground-state level and highly separated excited-state level under a tetragonal crystalline electric field (CEF), whose energy scale is much larger than the transition temperature. To understand the sequence of the phase transition from the paramagnetic phase, antiferroquadrupolar phase, and antiferromagnetic phase when decreasing the temperature, we examine the important interaction parameters in the effective localized model. We clarify that the 3z 2 − r 2 -type of the antiferroquadrupolar interactions can renormalize the CEF level splitting, which assists a quadrupolar ordering even in a tetragonal system without orbital degeneracy. Moreover, the stability of the antiferroquadrupolar and antiferromagnetic states in a magnetic field and the behavior of the magnetic/quadrupolar susceptibility are also presented for the information to identify the unknown order parameter in the nonmagnetic ordered phase.

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