Effect of pressure on magnetism of UIrGe

We report the effect of hydrostatic pressure on the electronic state of the antiferromagnet UIrGe, which is isostructural and isoelectronic with the ferromagnetic superconductors UCoGe and URhGe. A series of electrical resistivity measurements in a piston-cylinder-type cell and a cubic-anvil cell were performed at hydrostatic pressures up to 15 GPa. The Neel temperature decreases with increasing pressure. We constructed a p-T phase diagram and estimated the critical pressure pc, where the antiferromagnetism vanishes, as ∼12 GPa. The antiferromagnetic=paramagnetic transition appears to be first order. We suggest a scenario of competing antiferromagnetic inter-J- and ferromagnetic intra-J+-chain interactions in UIrGe. A moderate increase in the effective electron mass was detected in the vicinity of pc. A discussion of the electronic specific heat γ and electron-electron correlation term A using the Kadowaki-Woods relation is given.