Superconductivity, magnetism, and intermediate-valence phenomena in rare earth transition metal borides
An investigation of the interplay between long-range magnetic order and superconductivity in pseudoternary Ho(Rh/sub 1-x/Ir/sub x/)/sub 4/B/sub 4/ and Dy(Rh/sub 1-x/Ir/sub x/)/sub 4/B/sub 4/ systems was carried out by means of low temperature specific heat measurements. The properties of the intermediate valent compounds CeT/sub 3/B/sub 2/ and UT/sub 3/B/sub 2/ (T = CO, Ru, Rh, and Ir), as well as the behavior of superconductivity and ferromagnetism in pseudoternary Ce(Ru/sub 1-x/Rh/sub x/)/sub 3/B/sub 2/ compounds, were characterized by low temperature specific heat, electrical resistivity, and magnetic measurements. A low temperature phase diagram vs alloy composition was determined for Ho(Rh/sub 1-x/Ir/sub x/)/sub 4/B/sub 4/. The specific heat features associated with long-range ordering of the Ho/sup +3/ magnetic moments suggest mean field theory ferromagnetism for x less than or equal to 0.2. Antiferromagnetic ordering was observed for x greater than or equal to 0.2 and antiferromagnetic spin wave behavior was found for the ordered Ho/sup +3/ moments for x greater than or equal to 0.5. Unusual magnetic ordering occurs for 0.275 less than or equal to x less than or equal to 0.4 including two distinct magnetic transitions. The compound CeRh/sub 3/B/sub 2/ exhibits ferromagnetic ordering for T less than or equal to 113 K with a saturation magnetic moment 0.37 ..mu../sub B/ per formula unit, while CeRu/sub 3/B/sub 2/ exhibits superconductivity below 0.68 K. Values of the electronic specific heat coefficient ..gamma.. for the compounds range from 9.7 mJ/mol-K/sup 2/ for CeCo/sub 3/B/sub 2/ to 64 mJ/mol-K/sup 2/ for UIr/sub 3/B/sub 2/. A phase diagram of the transition temperatures vs alloy composition was determined for Ce(Ru/sub 1-x/Rh/sub x/)/sub 3/B/sub 2/. Superconductivity of CeRu/sub 3/B/sub 2/ disappears for Rh substitution x greater than or equal to 0.38.
- Research Organization:
- California Univ., San Diego (USA)
- OSTI ID:
- 5392932
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ACTINIDE COMPOUNDS
BORIDES
BORON COMPOUNDS
CERIUM BORIDES
CERIUM COMPOUNDS
COBALT BORIDES
COBALT COMPOUNDS
DIAGRAMS
DYSPROSIUM BORIDES
DYSPROSIUM COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HOLMIUM BORIDES
HOLMIUM COMPOUNDS
IRIDIUM BORIDES
MAGNETIC PROPERTIES
PHASE DIAGRAMS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REFRACTORY METAL COMPOUNDS
RHODIUM BORIDES
RHODIUM COMPOUNDS
RUTHENIUM BORIDES
RUTHENIUM COMPOUNDS
SUPERCONDUCTIVITY
TRANSITION ELEMENT COMPOUNDS
URANIUM BORIDES
URANIUM COMPOUNDS
VALENCE