Spin-fluctuation effects in CeSi/sub x/ alloys: High-field heat-capacity, magnetic susceptibility, and electrical resistivity studies, and a comment on TiBe/sub 2/

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.36.341· OSTI ID:6048544

Dhar, S K; Gschneidner, Jr, K A; Lee, W H; Klavins, P; Shelton, R N

The low-temperature (1.5--20 K) heat capacity in zero and applied fields up to 9.8 T, the magnetization in a field of 1.8 T in the range 1.5--300 K, the low-field ac magnetic susceptibility (50 mK--10 K), and electrical resistivity (2.4--300 K) have been measured for CeSi/sub x/ (x = 1.83, 1.85, and 1.90) alloys. A contribution of the form T/sup 3/lnT to the heat capacity, predicted for spin-fluctuation compounds by the paramagnon theory, occurs for all three compounds. In CeSi/sub 1.83/ and CeSi/sub 1.85/ the deviation from T/sup 3/lnT behavior occurs below approximately 8 and 2.4 K, respectively, due to the onset of magnetic order at 5.5 and 1 K, respectively. The transition of the spin-fluctuation regime to a magnetically ordered state in these two alloys is reported for the first time. In CeSi/sub 1.83/ the entropy associated with magnetic ordering accounts for approximately 17% of the theoretically expected R ln2 entropy; the rest is presumably associated with the spin fluctuations. Spin fluctuations in CeSi/sub 1.90/ are not quenched in fields up to 7.5 T, but the data suggest that the quenching may be starting at 10 T. The heat capacity in applied fields develops a bump which is presumably due to the development of a magnetic moment induced by the field. A similar such bump in TiBe/sub 2/ may also occur. A gradual progression from paramagnetic spin or valence fluctuations to magnetically ordered Kondo regime takes place with decreasing silicon concentration. An analysis of these data indicate that the CeSi/sub x/ alloys are moderately heavy fermions with ..gamma.. values of 184.6--269.6 mJ/mol Ce K/sup 2/, T/sub s/ (spin fluctuation temperature) values of 28 and 29 K, and Stoner enhancements varying from 135 to 645.

• Research Organization: Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011
• OSTI ID: 6048544
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 36:1; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALKALI METAL COMPOUNDS
ALLOYS
ANGULAR MOMENTUM
CESIUM COMPOUNDS
CESIUM SILICIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENTROPY
FLUCTUATIONS
KONDO EFFECT
LOW TEMPERATURE
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
MEDIUM TEMPERATURE
ORDER-DISORDER TRANSFORMATIONS
PARTICLE PROPERTIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
QUENCHING
SILICIDES
SILICON COMPOUNDS
SPECIFIC HEAT
SPIN
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ULTRALOW TEMPERATURE
VARIATIONS
VERY LOW TEMPERATURE