Anisotropic magnetic coupling with a two-dimensional characteristic in noncentrosymmetric Cr11Ge19

Abstract

In this work, we successfully synthesize the single crystal Cr11Ge19. The magnetism of the noncentrosymmetric Cr11Ge19 with itinerant ferromagnetic ground state is thoroughly investigated on the single crystal. Based on the variation measurements including the angular rotation, temperature, and magnetic field dependence of magnetization, we find that this material exhibits strong magnetic anisotropy along the c-axis. To clearly reveal the magnetic interactions, the critical behavior is studied using the modified Arrott plot, the Kouvel-Fisher method, and the critical isotherm technique. Combining these different methods, three main critical exponents (β, γ, and δ) are obtained. The critical exponent β is close to the theoretical prediction of a three-dimensional XY model with spin-dimensionality n = 2, indicating two-dimensional magnetic coupling. Meanwhile, the critical exponent γ suggests that the magnetic interaction is of long-range type with magnetic exchange distance decaying as J(r) ≈ r−4.61. We propose that the ferromagnetic ground state of Cr11Ge19 is formed by the polarized magnetic moments along the c-axis, while the long-range magnetic coupling is established within the ab plane.

Low-Field Bi-Skyrmion Formation in a Noncentrosymmetric Chimney Ladder Ferromagnet

“…1(f)], and easy axis turns out to be along the [001] axis. The saturation magnetization M s is 0.51 μ B =Cr at 10 K. These magnetic properties are in good agreement with previous reports [25][26][27].…”

“…1(d) and 1(e). Cr 11 Ge 19 is characterized by a ferromagnetic exchange interaction with easy-axis anisotropy as well as by the noncentrosymmetric D 2d lattice [25,26], and, therefore, both types of Skyrmion formation mechanisms as introduced above may potentially be active depending on the relative magnitude of each magnetic interaction.…”

Topological Hall effect and the magnetic states of Nowotney chimney ladder compound Cr$_{11}$Ge$_{19}$}

“…We first present the magnetic field, H, dependence of the magnetization, M , with H parallel and perpendicular to the c-axis at 50 K in Fig. 2 urated magnetic moment is small ∼ 0.6 µ B at 50 K and 5 T, consistent with previous reports 15,[18][19][20] . In Fig.…”

“…1(c). We measured the chemical composition of these crystals via EDX spectra with the composition determined to be Cr 38.3±2.2 Ge 61.7±2.7 , well within the range expected for a Novotney Chimney ladder compound and in accordance with the previous reports 18,19 . The crystal structure and orientation are determined through single crystal x-ray diffraction.…”

“…Single crystals of Cr 11 Ge 19 were grown by a chemical vapor transport (CVT) method making use of the natural temperature gradient of a tube furnace. About 2.5 g of Cr and Ge powder was sealed in a quartz tube with a molar ratio of 45:55 18 . About 70-100 mg Iodine ( 2.2 mg/CC) was used as transfer agent.…”