Ferromagnetism of single crystal Fe[S2CN(C2D5)2]2Cl

Abstract

The fully deuterated form of previously studied Fe[S2CN(C2H5)2]2Cl, needed for neutron diffraction and scattering measurements, has been prepared for the first time and its magnetic behavior in single crystal form studied at low temperatures. Susceptibility and magnetization data show that Fe[S2CN(C2D5)2]2Cl has extremely similar magnetic anisotropy to the normal material: the monoclinic [101] direction is the only easy axis of ferromagnetism, with the orthogonal [010] and (1̄01)⊥ axes even showing antiferromagnetic-like maxima in their χ(T) near Tc. Only along [101] does M approach saturation at low fields. Analysis of χ(T) in the paramagnetic regime, assuming axial and rhombic crystal field distortions described by H= D[Ŝ32z−S(S+1)/3]+E[Ŝ32x −Ŝ32y] and including exchange interactions in a mean field approximation, leads to D/k=−3.03(5) K, E/k=−0.49(4) K, and zJ/k=0.99(3) K along with gx=2.058(20), gy=2.060(20), and gz=2.080(20). These parameters are rather similar to those of the normal material, though zJ/k is significantly larger. The ordering temperature, obtained from a critical law fit to [101] data in a small field, i.e., χ0=Γt−γ, is Tc=2.486(2) K, with γ=1.16(1) and Γ=1.07(5) emu/mol. The critical exponent γ is the same as in the normal material and corresponds to the theoretical value in Kawamura’s Z2×S1 model. An ∼1.2% enhancement in Tc over that of the normal material occurs, which may be due to slightly closer molecular packing. 75.30.Kz, 75.30.Cr, 75.30.Gw, 75.40.Cx