[sup 209]Bi NMR and NQR investigation of the small-gap semiconductor Ce[sub 3]Bi[sub 4]Pt[sub 3]

Journal Article · Wed Jun 15 04:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.16321· OSTI ID:7205542

Reyes, A P; Heffner, R H; Canfield, P C; Thompson, J D; Fisk, Z ^[1]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

We report measurements of the temperature dependence of the [sup 209]Bi nuclear quadrupole resonance frequency [nu][sub [ital Q]], the Knight shift [ital K], and the spin-lattice relaxation rate 1/[ital T][sub 1] in the small-gap semiconductor Ce[sub 3]Bi[sub 4]Pt[sub 3] between 1.8 and 300 K. Corresponding measurements also are reported for the nonmagnetic metallic isomorph La[sub 3]Bi[sub 4]Pt[sub 3]. The [nu][sub [ital Q]] data in the Ce compound show a characteristic departure from metallic-to-insulating behavior when the sample is cooled below [ital T][sub [ital M]]=80 K, the temperature of the susceptibility maximum, attributable to a loss of low-frequency vibrational modes in the insulating state. The Knight shift has both isotropic and axial components; this anisotropy originates from the presence of Ce via a transferred hyperfine coupling between Ce 4[ital f] and conduction electrons. An [ital s]-[ital f] exchange constant [ge]0.4 eV is found, consistent with hybridization in other rare-earth intermetallic compounds. A change in the scaling between the susceptibility and both the isotropic and axial Knight shifts at temperature [ital T][sub [ital M]] provides evidence that hybridization between the Ce 4[ital f] orbitals and the conduction electrons is responsible for the gap structure. The temperature dependence of the 1/[ital T][sub 1] data is consistent with a model electronic density of states possessing a temperature-independent gap [delta] of 180 K and a bandwidth of the order of 1600 K. The temperature dependence of 1/[ital T][sub 1] can also be fit well with a temperature-dependent gap with [delta](0) also [approx]180 K.

• OSTI ID: 7205542
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:23; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
BISMUTH ALLOYS
CERIUM ALLOYS
ENERGY GAP
ENERGY LEVELS
EXCITED STATES
HYPERFINE STRUCTURE
INTERMETALLIC COMPOUNDS
KNIGHT SHIFT
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MATERIALS
NUCLEAR QUADRUPOLE RESONANCE
PHYSICAL PROPERTIES
PLATINUM ALLOYS
PLATINUM METAL ALLOYS
RARE EARTH ALLOYS
RELAXATION
RELAXATION TIME
RESONANCE
SEMICONDUCTOR MATERIALS
SPIN-LATTICE RELAXATION
TEMPERATURE DEPENDENCE
VIBRATIONAL STATES