Antiferromagnetism in EuNiGe3

Abstract

The synthesis and crystallographic and physical properties of polycrystalline EuNiGe3 are reported. EuNiGe3 crystallizes in the noncentrosymmetric body-centered tetragonal BaNiSn3-type structure (space group I4mm), in agreement with previous reports, with the Eu atoms at the corners and body center of the unit cell. The physical property data consistently demonstrate that this is a metallic system in which Eu spins S = 7/2 order antiferromagnetically at a temperature TN = 13.6 K. Magnetic susceptibility χ data for T > TN indicate that the Eu atoms have spin 7/2 with g = 2, that the Ni atoms are nonmagnetic, and that the dominant interactions between the Eu spins are ferromagnetic. Thus we propose that EuNiGe3 has a collinear A-type antiferromagnetic structure, with the Eu ordered moments in the ab-plane aligned ferromagnetically and with the moments in adjacent planes along the c-axis aligned antiferromagnetically. A fit of χ(T ≤ TN) by our molecular field theory is consistent with a collinear magnetic structure. Electrical resistivity ρ data from TN to 350 K are fitted by the Bloch-Grüneisen model for electron-phonon scattering, yielding a Debye temperature of 265(2) K. A strong decrease in ρ occurs below TN due to loss of spin-disorder scattering. Heat capacity data at 25 K ≤ T ≤ 300 K are fitted by the Debye model, yielding the same Debye temperature 268(2) K as found from ρ(T ). The extracted magnetic heat capacity is consistent with S = 7/2 and shows that significant short-range dynamical spin correlations occur above TN. The magnetic entropy at TN = 13.6 K is 83% of the expected asymptotic high-T value, with the remainder recovered by 30 K.

Itinerant and local-moment magnetism inEuCr2As2single crystals

“…5). The hump in the ordered state is particularly noticeable in compounds containing Eu 2+ or Gd 3+ with S = 7/2, and is not visible for lower S, e.g., S = 1/2 [36,37,38]. The magnetic contribution to the entropy S mag was obtained by integrating the C mag /T versus T .…”

Synthesis, crystal structure and physical properties of EuTGe3 (T = Co, Ni, Rh, Pd, Ir, Pt) single crystals

“…EuPtGe 3 was found to order below T N = 11 K with a commensurate equal-moment (EM) antiferromagnetic (AFM) structure with the magnetic moments confined within the basal a-b plane [14]. In subsequent investigations, the magnetic properties of polycrystalline samples of EuPdGe 3 and EuNiGe 3 were determined [15,16]. For both compounds a single AFM phase transition was evidenced to occur at T N = 12.4 K and 13.6 K, respectively.…”

“…Nevertheless, based on the obtained data, it was suggested in Ref. [16] that EuNiGe 3 possesses a collinear EM-AFM structure with the europium spins being aligned ferromagnetically in the a-b plane and coupled ferromagnetically along the c-axis. In the most recent study [17], however, made on single crystals of EuNiGe 3 , it was revealed that the EM-AFM arrangement occurs only below T N2 % 10.5 K, with the magnetic moments being almost parallel to the c-axis, while in the intermediate temperatures up to T N1 % 13.2 K, the AFM structure has probably an incommensurate amplitude-modulated (AM) character.…”

Low-Temperature Physical Properties of Single-Crystalline EuCoGe3and EuRhGe3

“…In the rst literature report [10], based on polycrystalline data, the compound was described as a simple A-type collinear antiferromagnet with T N = 13.6 K. However, in the most recent study on single crystals [11] In this contribution, we report on the low-temperature physical behaviours in the two novel representatives of the EuTGe 3 series, namely EuCoGe 3 and EuRhGe 3 .…”