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Field‐induced quantum criticality – application to magnetic cooling
Author(s) -
Lang Michael,
Wolf Bernd,
Honecker Andreas,
Balents Leon,
Tutsch Ulrich,
Cong Pham Than,
Hofmann Georg,
Krüger Natalia,
Ritter Franz,
Assmus Wolf,
Prokofiev Andrey
Publication year - 2013
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201200794
Subject(s) - condensed matter physics , quantum critical point , magnetic refrigeration , physics , magnetic field , criticality , quantum , paramagnetism , quantum phase transition , critical point (mathematics) , critical field , phase transition , quantum mechanics , magnetization , mathematical analysis , mathematics , nuclear physics
Materials close to a quantum‐critical point – a zero‐temperature phase transition – exhibit anomalous thermodynamic properties also at finite temperatures. Close to a magnetic field‐induced quantum‐critical point, for example, the finite‐temperature entropy S T shows strong variations upon varying the magnetic field. Here we discuss the possibility to use this accumulation of entropy around a field‐induced quantum‐critical point for realizing an efficient magnetic cooling. Our proof‐of‐principle demonstration is based on measurements and theoretical calculations of the magnetocaloric properties of low‐dimensional spin‐1/2 antiferromagnets close to their field‐induced quantum‐critical points. We present results of the magnetocaloric effect Γ B = T −1 (∂ T /∂ B ) S ≈ const as a function of both field and temperature in the vicinity of the quantum‐critical point and discuss various performance characteristics, such as range of operation, efficiency and hold time. These figures are compared with those of a state‐of‐the‐art paramagnetic coolant.