Magnetic field and pressure phase diagrams of uranium heavy-fermion compound U2Zn17

We have performed magnetization measurements at high magnetic fields of up to 53 T on single crystals of a uranium heavy-fermion compound U2Zn17 grown by the Bridgman method. In the antiferromagnetic state below the Neel temperature TN=9.7 K, a metamagnetic transition is found at Hc≅32 T for the field along the [112-bar0] direction (a-axis). The magnetic phase diagram for the field along the [112-bar0] direction is given. The magnetization curve shows a nonlinear increase at Hm≅35 T in the paramagnetic state above TN up to a characteristic temperature Tχmax where the magnetic susceptibility or electrical resistivity shows a maximum value. This metamagnetic behavior of the magnetization at Hm is discussed in comparison with the metamagnetic magnetism of the heavy-fermion superconductors UPt3, URu2Si2, and UPd2Al3. We have also carried out high-pressure resistivity measurement on U2Zn17 using a diamond anvil cell up to 8.7 GPa. Noble gas argon was used as a pressure-transmitting medium to ensure a good hydrostatic environment. The Neel temperature TN is almost pressure-independent up to 4.7 GPa and starts to increase in the higher-pressure region. The pressure dependences of the coefficient of the T2 term in the electrical resistivity A, the antiferromagnetic gap Δ, and the characteristic temperature Tρmax are discussed. It is found that the effect of pressure on the electronic states in U2Zn17 is weak compared with those in the other heavy fermion compounds. (author)