Itinerant-electron metamagnetic transition in LaFe12B6

• LaFe12B6 is an itinerant-electron antiferromagnet with 0.36 μB/Fe-atom in the ground state.
• The metamagnetic transition occurs below and above the Néel temperature.
• The kinetic arrest takes place at low temperatures.
• The magnetic phase diagram exhibits a critical end point.
• Large magnetocaloric effects are obtained due to the metamagnetic transition.

LaFe12B6 (SrNi12B6-type) is an antiferromagnet with a low moment of 0.36 μB/Fe-atom in the ground state. The field-induced first-order transition takes place in a wide range of temperature including below and above the Néel temperature of 35 K. This transition results in a high moment of 1.6 μB/Fe-atom, being characteristics of the itinerant-electron metamagnetic transition. The critical magnetic field of the metamagnetic transition BC increases with increasing temperature except for low temperature ranges, in which the kinetic arrest occurs. Above the arrested temperature, the sign of the temperature dependence of dBC/dT is positive. The metamagnetic transition brings about large magnetocaloric effects, that is, a large negative value of the isothermal magnetic entropy change, ΔSm, and a large positive value of the adiabatic temperature change, ΔTad.