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Abstract |
The magnetocaloric effect, i.e., the change of temperature induced by an adi-
abatic change of an external magnetic field was discovered by Warburg in 1881
during his investigations of iron. Subsequently, back in 1933, cooling by adia-
batic demagnetization of paramagnetic salts was the first method to reach tem-
peratures below 1 K. Until today, adiabatic demagnetization remains the method
of choice to cool solids to the milli-Kelvin range or below. In addition, cooling
by adiabatic demagnetization at intermediate temperatures (Kelvin-range) is un-
der discussion for space applications and future linear colliders. Such applica-
tions would benefit from more efficient materials. On this background, we re-
view recent ideas how to go beyond single-ion systems, and exploit interactions
between magnetic moments of dipolar or Heisenberg nature to enhance mag-
netocaloric properties. Specifically, we discuss the enhanced magnetocaloric
effect observed in geometrically frustrated magnets and close to field-induced
quantum phase transitions. |
