Superconductivity and Magnetism of Dy_1-xY_xRh₄B₄: Candidate for Spin-Triplet Cooper Pairing

Abstract

In this work for the first time we give the evidence that compound Dy 1−x Y x Rh 4 B 4 with the tetragonal body-centered crystal structure LuRu4B4 is the ferrimagnetic at temperatures TCur < 40 K, ferrimagnetic superconductor at T C < 10 K and antiferromagnetic superconductor at TN < 3 K. No reentrant behavior was found down to T = 0.32 K. For the first time by means of a method of microcontact spectroscopy of the Andreev reflection in point contact Ag-Dy0.8Y0.2Rh4B4 the value and temperature and field dependences of superconducting gap parameter ∆(T, H) in Dy 0.8 Y 0.2 Rh 4 B 4 were determined. The value of the ratio 2∆(0)/kT C is about 4. Some unusual features of ∆(T, H) dependences were observed, which give the evidence that the Dy 1−x Y x Rh 4 B 4 is a candidate for spintriplet Cooper pairing of charges with the parallel spins.

Point-contact Andreev reflection spectroscopy of a magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4

“…The authors analyzed the magnetic and resistive characteristics of some samples and concluded that the triplet type pairing was quite possible at certain temperatures. Later [11,12] the first transition was identified as ferrimagnetic, in which case the magnetic structure consists of two sublattices with unequal and opposite directed magnetic moments. This however does not prohibit its coexistence with superconductivity.…”

“…A compound of this family (Dy 0.8 Y 0.2 Rh 4 B 4 ) was used to form a point contact (PC) with Au, and the Andreev reflection spectra dI/dV(V) [11][12][13] and the dependence H c2 (T) were measured on it in a wide range of temperatures and magnetic fields. By analyzing the measured spectra the authors obtained the temperature, ∆(T), and magnetic field, ∆(H), dependences of the order parameter.…”

Anisotropy of electric resistance and upper critical field in magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4

“…The physical properties of quadruple compounds Dy 1−x Y x Rh 4 B 4 having a body-centered tetragonal LuRu 4 B 4 -type crystal structure deserve special attention due to a great number of interesting features of these materials. For instance, it was found [2,3] that the magnetic ordering of Dy atoms may occur at the temperature T M higher than the superconducting transition temperature T c and coexist with superconductivity down to very low temperatures. It was established in [3] that Dy 1−x Y x Rh 4 B 4 belongs to materials with intrinsic ferrimagnetism, and the transition temperature T M strongly depends on the concentration of non-magnetic yttrium: it falls with increasing Y concentration from 37 K in DyRh 4 [2].…”

“…For instance, it was found [2,3] that the magnetic ordering of Dy atoms may occur at the temperature T M higher than the superconducting transition temperature T c and coexist with superconductivity down to very low temperatures. It was established in [3] that Dy 1−x Y x Rh 4 B 4 belongs to materials with intrinsic ferrimagnetism, and the transition temperature T M strongly depends on the concentration of non-magnetic yttrium: it falls with increasing Y concentration from 37 K in DyRh 4 [2]. Measurements of the specific heat of Dy 0.8 Y 0.2 Rh 4 B 4 (T M = 30.5 K, T c = 5.9 K) indicate emergence of another magnetic phase transition below 2.7 K [3].…”

Wohlleben effect in YRh4B4

“…12 These compounds have the feature that, with the appearance of superconductivity the magnetic ordering (ferromagnetism) does not vanish, but coexists with it down to the lowest experimentally attainable temperatures ($0.5 K). 13,14 We suggested that the internal magnetism of these compounds may play an important role in the development of the WE. In this regard, there is some interest in the question of whether this phenomenon occurs in isostructural nonmagnetic compounds.…”