From antiferromagnetic order to a field-polarised state in the heavy-fermion compound YbAgGe

Magnetisation measurements between 75 mK and 1 K were used to study the evolution up to magnetic fields of 8 T of the magnetic properties of the heavy-fermion metal YbAgGe. The magnetisation data confirms a first-order transition between two antiferromagnetic states, which is suppressed at 2 T. Close to 5 T, which is a field region where the known antiferromagnetic long-range order is already suppressed, the static linear susceptibility is enhanced, accompanied by a strong increase of the linear specific-heat coefficient. However, the enhancement of the static linear susceptibility is not strong enough to be alone responsible for the strong increase of the quasi-linear resistivity observed previously.