Superconductivity, magnetic properties, and specific heat of the pseudoternary, body-centered tetragonal system Ho(Rh /SUB 1-x/ Ru /SUB x/ )/sub 4/B/sub 4/

Journal Article · Mon Sep 01 04:00:00 EDT 1986 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00681706· OSTI ID:7195090

Thoma, A; Adrian, H; Meinett, A

The phase boundaries between superconductivity and various types of magnetism in the pseudoternary system Ho(Rh /SUB 1-x/ Ru /SUB x/ )/sub 4/B/sub 4/ were examined by lowtemperature measurements of the specific heat c(T), dc magnetization M(H), superconducting upper critical field H /SUB c2/ (T), and ac susceptibility X /SUB ac/ (T). For Ru concentrations X less than or equal to 0.37 superconductivity coexists with antiferromagnetic order below about 1 K, as shown by characteristic minima in the H /SUB c2/ (T) curves and an extrapolation of M(H) data. Additionally, the H /SUB c2/ (T) measurements exhibit an unusual hysteresis between data taken in increasing and decreasing fields below 0.6 K. As a starting point for a theoretical explanation of this feature, a mean-field model is proposed with antiferromagnetic as well as ferromagnetic interactions, which are tentatively identified as the RKKY and dipole-dipole interactions. The existence of two competing interactions is supported by the observation of a time-dependence of the X /SUB ac/ signal at 50 mK for 0.40 less than or equal to x less than or equal to 0.70, leading to a pronounced hysteresis in X /SUB ac/ (T), which reflects a relaxation of the magnetic structure with time constants of several hours. For xgreater than or equal to0.80 the X /SUB ac/ (T) and M(H) data indicate ferromagnetic ordering with T /SUB m/ increasing with x. However, an irregular temperature dependence of the Arrott plots for x=1.0 and unusual features of the magnetic c(T) anomalies for x=0.95 and 1.0 exclude simple mean-field ferromagnetism. A discussion of the experimental results based on an x-dependent variation of the electronic density of states at the Fermi level is presented.

• Research Organization: Univ. Erlangen. Nurnberg, Erlangen
• OSTI ID: 7195090
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 64:5/6; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ANTIFERROMAGNETISM
BORIDES
BORON COMPOUNDS
CRITICAL FIELD
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY LEVELS
ENERGY-LEVEL DENSITY
FERMI LEVEL
FERROMAGNETISM
HOLMIUM BORIDES
HOLMIUM COMPOUNDS
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETISM
MAGNETIZATION
MATHEMATICAL MODELS
ORDER PARAMETERS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REFRACTORY METAL COMPOUNDS
RHODIUM BORIDES
RHODIUM COMPOUNDS
RUTHENIUM BORIDES
RUTHENIUM COMPOUNDS
SPECIFIC HEAT
SUPERCONDUCTIVITY
TETRAGONAL LATTICES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
ULTRALOW TEMPERATURE