Magnetic ordering of the antiferromagnetCu2MnSnS4from magnetization and neutron-scattering measurements

Abstract

Magnetization and neutron-diffraction measurements were performed on a single crystal of Cu 2 MnSnS 4. This quartenary magnetic semiconductor has the stannite structure ͑derived from the zinc-blende structure which is common to many II-VI dilute magnetic semiconductors͒, and it orders antiferromagnetically at low temperature. The neutron data for the nuclear structure confirm that the space group is I42m. Both the neutron and magnetization data give T N ϭ8.8 K for the Néel temperature. The neutron data show a collinear antiferromagnetic ͑AF͒ structure with a propagation vector kϭ͓1/2,0,1/2͔, in agreement with earlier neutron data on a powder. However, the deduced angle between the spin axis and the crystallographic c direction is between 6°and 16°, in contrast to the earlier value of 40°. The magnetization curve at TӶT N shows the presence of a spin rotation ͑analogous to a spin flop͒, which indicates that the spin axis is indeed close to the c direction. The deduced magnetic anisotropy gives an anisotropy field H A Х2 kOe. At high magnetic fields the magnetization curve at TӶT N shows the transition between the canted ͑spin-flop͒ phase and the paramagnetic phase. The transition field, Hϭ245.5 kOe, yields an intersublattice exchange field H E ϭ124 kOe. The exchange constants deduced from H E and the Curie-Weiss temperature ⌰ϭϪ25 K show that the antiferromagnetic interactions are an order of magnitude smaller than in II-VI dilute magnetic semiconductors ͑DMS's͒. The much weaker antiferromagnetic interactions are expected from the difference in the crystal structures ͑stannite versus zinc-blende͒. A more surprising result is that the exchange constant which controls the AF order below T N is not between Mn ions with the smallest separation. This result contrasts with a prediction made for the related II-VI DMS, according to which the exchange constants decrease rapidly with distance. ͓S0163-1829͑97͒04234-3͔

Magnetically induced ferroelectricity inCu2MnSnS4andCu2

“…During structural optimization, a threshold on the atomic forces is set as 0.01 eV/Å. Internal atomic coordinates are optimized starting from experimental data of Cu 2 MnSnS 4 [10] and Cu 2 MnSnSe 4 . [16] The 2×4×1 Monkhost-Pack k-point grid in the Brillouin zone is used.…”

“…Lattice constants are fixed to the experimental data: a = b = 5.514Å, c = 10.789Å for Cu 2 MnSnS 4 [10] and a = b = 5.736Å, c = 11.401Å for Cu 2 MnSnSe 4 [16] in the tetragonal I42m structure. In order to impose the experimentally observed AFM spin configuration in Cu 2 MnSnS 4 [10] with the propagation vector k = ( (c)) (note that, to our knowledge, the experimental magnetic configuration for Cu 2 MnSnSe 4 has not been reported yet).…”

“…In order to impose the experimentally observed AFM spin configuration in Cu 2 MnSnS 4 [10] with the propagation vector k = ( (c)) (note that, to our knowledge, the experimental magnetic configuration for Cu 2 MnSnSe 4 has not been reported yet). Since the observed AFM configuration breaks the symmetries (except for C 2y ), ferroelectric polarization is allowed to be magnetically-induced along the y direction.…”

“…Moreover, the magnetization curve has suggested the spin quantization axis to be close * Electronic address: tetsuya.fukushima@aquila.infn.it to the c direction. [10] Additionally, the small dependence of susceptibility upon the direction of magnetic field implied a rather small magnetic anisotropy.…”

Spin-flop transition driven by competing magnetoelastic anisotropy terms in a spin-spiral antiferromagnet

“…Today, the term SFT is utilized in a broader sense, which includes a variety of field-driven spin-reorientation transitions in a wide spectrum of antiferromagnetic materials [4][5][6][7][8][9].…”