Anomalous thermal expansion in YMn2, Y6Mn23 and YMn12

Abstract The thermal expansion coefficient α ( T ) of YMn 2 , Y 6 Mn 23 and YMn 12 is presented in the temperature range 4.2–1000 K together with α ( T ) of YCo 2 and YNi 2 . The strong variation of α ( T ) of the YMn compounds in their paramagnetic state is discussed under the assumption that there exist Mn atoms with different electronic configurations and therefore with different atomic volumes. Changes of the concentration of these different Mn atoms with temperature reveal this anomalous thermal expansion.