Superconductivity and magnetism in the pseudoternary system Gd/sub x/Y/sub 1-x/Rh/sub 4/B/sub 4/
The phase boundaries between the paramagnetic, superconducting, and ferromagnetically ordered states of the tetragonal pseudoternary system Gd/sub x/Y/sub 1-x/Rh/sub 4/B/sub 4/ have been determined by ac susceptibility measurements. Magnetization measurements, performed with cylindrical samples for 0< or =x< or =0.45 at temperatures above 1.5 K, show clearly that macroscopic electromagnetic effects are of minor importance in this system and indicate a transition from type-II/2 to type-II/1 or type-I superconductivity at temperatures close to T/sub c/2. For the critical fields we obtain from the magnetization curves a sawtoothlike H/sub c/1(T), scaling with T/sub c/1(x), whereas H/sub c/2(T) is bell shaped for x> or =0.1, with its maximum decreasing exponentially with x for x< or =0.30. From Arrott plots we find spontaneous magnetizations below T/sub m/ and Curie-Weiss laws for the normal-state susceptibility indicating ferromagnetic Curie temperatures THETA/sub C/>0 for x>0.1. Analyzing the data we show that the strength of the exchange interaction between the conduction electrons and the Gd moments deduced from T/sub c/1(x) is strong enough to mediate the indirect interaction between the Gd moments as found from THETA/sub C/(x). From specific-heat measurements carried out for x = 0.25 and 0.45 we obtain N*(E/sub F/) = 0.57 states/(atomBeV spin), in agreement with the nonmagnetic Y and Lu compounds. The details of the magnetic transitions appear to scale with the Gd concentration.
- Research Organization:
- Physikalisches Institut der Universitaet Erlangen-Nuernberg, D-8520 Erlangen, Bundesrepublik Deutschland
- OSTI ID:
- 6774294
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 26:5
- Country of Publication:
- United States
- Language:
- English
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
GADOLINIUM BORIDES
FERROMAGNETISM
MAGNETIC SUSCEPTIBILITY
SUPERCONDUCTIVITY
RHODIUM BORIDES
YTTRIUM BORIDES
CRITICAL FIELD
CURIE-WEISS LAW
EXCHANGE INTERACTIONS
EXPERIMENTAL DATA
MAGNETIZATION
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
SCALING LAWS
SPECIFIC HEAT
TYPE-I SUPERCONDUCTORS
TYPE-II SUPERCONDUCTORS
ULTRALOW TEMPERATURE
BORIDES
BORON COMPOUNDS
DATA
DIAGRAMS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
GADOLINIUM COMPOUNDS
INFORMATION
INTERACTIONS
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETISM
NUMERICAL DATA
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
RHODIUM COMPOUNDS
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
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Electronic
Magnetic
Optical
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