title: Crystal structure and a giant magnetoresistance effect in the new Zintl compound Eu3Ga2P4.
abstract: Single-crystalline samples of a new Zintl compound, Eu(3)Ga(2)P(4), have been synthesized by a Ga-flux method. Eu(3)Ga(2)P(4) is found to crystallize in a monoclinic unit cell, space group C2/c, isostructural to Ca(3)Al(2)As(4). The structure is composed of a pair of edge-shared GaP(4) tetrahedra, which link by corner-sharing to form Ga(2)P(4) two-dimensional layers, separated by Eu(2+) ions. Magnetic susceptibility showed a Curie-Weiss behavior with an effective magnetic moment consistent with the value for Eu(2+) magnetic ions. Below 15 K, ferromagnetic ordering was observed and the saturation magnetic moment was 6.6 μ(B). Electrical resistivity measurements on a single crystal showed semiconducting behavior. Resistivity in the temperature range between 280 and 300 K was fit by an activation model with an energy gap of 0.552(2) eV. The temperature dependence of the resistivity is better described by the variable-range-hopping model for a three-dimensional conductivity, suggesting that Eu-P bonds are involved in the conductivity. A large magnetoresistance, up to -30%, is observed with a magnetic field H = 2 T at T = 100 K, suggesting strong coupling of carriers with the Eu(2+) magnetic moment.
authors.affiliation: National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047, Japan. tsujii.naohito@nims.go.jp
authors.forename: Naohito
authors.initials: N
authors.lastname: Tsujii
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Uvarov
authors.forename: Peter
authors.initials: P
authors.lastname: Klavins
authors.forename: Tanghong
authors.initials: T
authors.lastname: Yi
authors.forename: Susan M
authors.initials: SM
authors.lastname: Kauzlarich