Putative quantum critical point in the itinerant magnet ZrFe_4Si_2 with a frustrated quasi-one-dimensional structure

摘要

The Fe sublattice in the compound ZrFe_4Si_2 features geometrical frustration and quasi-one-dimensionality. We therefore investigated the magnetic behavior in ZrFe_4Si_2 and its evolution upon substituting Ge for Si and under the application of hydrostatic pressure using structural, magnetic, thermodynamic, and electrical-transport probes. Magnetic measurements reveal that ZrFe_4Si_2 holds paramagnetic Fe moments with an effective moment μ_(eff) = 2.18μ_B. At low temperatures the compound shows a weak short-range magnetic order below 6 K. Our studies demonstrate that substituting Ge for Si increases the unit-cell volume and stabilizes the short-range order into a long-range spin-density wave type magnetic order. On the other hand, hydrostatic pressure studies using electrical-resistivity measurements on ZrFe_4(Si_(0.88)Ge_(0.12) 2 indicate a continuous suppression of the magnetic ordering upon increasing pressure. Therefore, our combined chemical substitution and hydrostatic pressure studies suggest the existence of a lattice-volume-controlled quantum critical point in ZrFe_4Si_2.