Specific Heat of Mg{sup 11}B{sub 2} : Evidence for a Second Energy Gap
Measurements of the specific heat of Mg{sup 11}B {sub 2} from 1 to 50K, in magnetic fields to 9T, give the Debye temperature, {Theta}=1050 K , the coefficient of the normal-state electron contribution, {gamma}{sub n}=2.6 mJ mol{sup -1} K{sup -2} , and a discontinuity in the zero-field specific heat of 133 mJmol {sup -1} K{sup -1} at T{sub c}=38.7 K . The estimated value of the electron-phonon coupling parameter, {lambda}=0.62 , could account for the observed T{sub c} only if the important phonon frequencies are unusually high relative to {Theta} . At low T , there is a strongly field-dependent feature that suggests the existence of a second energy gap, about 4 times smaller than the major gap.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AC03-76SF00098; W-31109-ENG-38
- OSTI ID:
- 40277206
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 4 Vol. 87; ISSN 0031-9007
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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