Magnon contribution to specific heat of the magnetic superconductor HoNi2B2C

Autor: M. El Massalami, F. A. B. Chaves, R. E. Rapp
Rok vydání: 2001
Předmět:
Zdroj: Journal of Magnetism and Magnetic Materials. :476-478
ISSN: 0304-8853
DOI: 10.1016/s0304-8853(00)00975-6
Popis: Below 5 K, the quaternary intermetallic borocarbide HoNi 2 B 2 C shows a coexistence of superconductivity and commensurate antiferromagnetism. Since such a magnetic ground structure consists of ferromagnetic HoC layers that are weakly coupled antiferromagnetically, it is interesting to investigate the character and dimensionality of its low-temperature spin-wave excitations. For that purpose, low-temperature calorimetric studies were carried out on a well-characterized polycrystalline HoNi 2 B 2 C sample. After a proper subtraction of the nuclear, electronic and lattice contributions, the remaining part of the specific heat below 5 K, which is due solely to the spin-wave excitations, can be expressed as 0.29 T 3 exp(−5.3/ T ) J/mol K. In agreement with the known magnetic structure, the T 3 factor is a signature of a three-dimensional antiferromagnetic character while the exponential factor emphasizes the presence of an energy gap ( Δ =5.3±0.2 K) in the spin-wave excitation; the magnitude of which equals the strength of the magnetic order ( T N ≈5 K).
Databáze: OpenAIRE