Tuning Magnetic and Transport Properties in Quasi-2D (Mn1−xNix)2P2S6 Single Crystals

Abstract

We report an optimized chemical vapor transport method to grow single crystals of (Mn1−xNix)2P2S6 where x = 0, 0.3, 0.5, 0.7, and 1. Single crystals up to 4 mm × 3 mm × 200 μm were obtained by this method. As-grown crystals are characterized by means of scanning electron microscopy and powder X-ray diffraction measurements. The structural characterization shows that all crystals crystallize in monoclinic symmetry with the space group C2/m (No. 12). We have further investigated the magnetic properties of this series of single crystals. The magnetic measurements of the all as-grown single crystals show long-range antiferromagnetic order along all principal crystallographic axes. Overall, the Néel temperature TN is non-monotonous; with increasing Ni2+ doping, the temperature of the antiferromagnetic phase transition first decreases from 80 K for pristine Mn2P2S6 (x = 0) up to x = 0.5 and then increases again to 155 K for pure Ni2P2S6 (x = 1). The magnetic anisotropy switches from out-of-plane to in-plane as a function of composition in (Mn1−xNix)2P2S6 series. Transport studies under hydrostatic pressure on the parent compound Mn2P2S6 evidence an insulator-metal transition at an applied critical pressure of ~22 GPa.

Crystal Growth and Anisotropic Magnetic Properties of Quasi-2D (Fe$_{1-x}$Ni$_{x}$)$_{2}$P$_{2}$S$_{6}$

“…This two-step process has proven necessary to obtain homogeneous single crystals with the desired degree of Ni-substitution. A similar approach was used by us for the crystal growth in the closely related substitution series (Mn 1−x Ni x ) 2 P 2 S 6 [22].…”

“…The origin of the observed abrupt evolution of the magnetic anisotropy around x Ni may be subject to future investigations, for example if it can be continuously tuned from Ising-like to XXZ-like in the narrow regime between (Fe 0.1 Ni 0.9 ) 2 P 2 S 6 and Ni 2 P 2 S 6 . Also, it will be interesting to compare the evolution of the magnetic behavior and anisotropy of (Fe 1−x Ni x ) 2 P 2 S 6 in detail to closely related systems, such as (Mn 1−x Fe x ) 2 P 2 S 6 [20] and (Mn 1−x Ni x ) 2 P 2 S 6 [22]. Finally, we emphasize that crystals grown in this work may also allow to study the substitution dependence of electronic properties within this series.…”

Crystal Growth, Exfoliation and Magnetic Properties of Quaternary Quasi-Two-Dimensional CuCrP$_2$S$_6$

“…Please note that the Cu1 site is empty and only listed here for comparison with the structure proposed by Colombet et al[17].crystal structure model in C2/c. If, in contrast, Cu and Cr would have the same oxidation state of 2+, a random distribution of these ions on the M sites on the honeycomb lattice would be rather expected, as, e.g., observed for FeNiP 2 S 6 and other homocharge substituted M 2 P 2 S 6 compounds[28,31,32].…”

Crystal Growth of the Quasi-2D Quarternary Compound AgCrP$_2$S$_6$ by Chemical Vapor Transport

“…No additional reflection were observed demonstrating the phase purity of our crystals. The C2/m space group, which is typically observed for compounds of the M 2 P 2 S 6 family [19,22], including M 2+ M 2+ P 2 S 6 compounds of isovalent substitution series (e.g., MnFeP 2 S 6 [10], MnNiP 2 S 6 [11] and FeNiP 2 S 6 [13]), can be ruled out. Assuming a monoclinic unit cell, several observed reflections correspond to Laue indices that are systematically absent for C centering, as they violate the reflection condition hkl: h + k = 2n.…”

“…(Mn 1−x Ni x ) 2 P 2 S 6 [11], (Fe 1−x Ni x ) 2 P 2 S 6 [12,13] and (Zn 1−x Ni x ) 2 P 2 S 6 [4]) are reported to exhibit solid solution behavior and, thus, imply a random distribution of the substituents on the honeycomb network, as illustrated in Fig. 1(a).…”