Magnetoelasticity andH−Tphase diagram ofTbNi2B2

M. ElMassalami

¹

,

M. Amara

²

,

Rose-Marie Galéra

³

et al.

Abstract

We investigated the magnetoelastic and magnetic properties of single-crystal TbNi 2 B 2 C within the paramagnetic and ordered phases and along both a and c axes. The measured paramagnetic and gamma-parastriction susceptibilities are satisfactorily reproduced by the theoretical calculations based on crystalline electric field and molecular field approximations. The features of the ␥-symmetry lowering mode indicate a noticeable orthorhombic distortion within both paramagnetic and magnetically ordered regions. The H-T phase diagram ͑H ʈ a͒ reveals a cascade of transformations that delineate the phase boundaries between a weak-ferromagnetic ͑WF͒ phase, an intermediate phase, and a paramagnetic saturated state. Interestingly, below 9 K and within the low-field regime, the phase boundary enclosing the WF state shows a reentrant behavior. Such a reentrance feature is associated with the presence of the net ferromagnetic component below T WF .

Magnetoelastic phase diagram ofTbNi2B2C

“…A further testament to the complexity of the nickel borocarbides is the presence of a magnetoelastic coupling, where the AFM order parameter gives rise to lattice distortions [17][18][19]. Several of the borocarbides systems exhibit spin density wave (SDW) magnetic order with propagation vector q ∼ (0.55,0,0) [20,21].…”

“…At the Néel temperature, the system undergoes a structural phase transition from tetragonal to orthorhombic crystal structure [38]. For fields along [100], the phase diagram 2469-9950/2018/97(22)/224417 (8) 224417-1 ©2018 American Physical Society of TbNi 2 B 2 C is exceedingly complex [19]. The crystal studied in Ref.…”

“…The lattice displacements are not along the c axis as found in the quadrupolar phase of superconducting TmNi 2 B 2 C, but along the a axis. So while 4 is crucial for understanding the magnetoelastic deformations in TmNi 2 B 2 C, the magnetoelastic Hamiltonian in TbNi 2 B 2 C looks to be more similar to that of ErNi 2 B 2 C [19,41].…”

Tuning in magnetic modes in Tb(CoxNi1−x)2BElMassalami1, Takeya2, Ouladdiaf3 et al. 2012Phys. Rev. BSelf Cite8080View full textAdd to dashboardCite

“…The moment orientation for each composition was taken to be along the a axis of the nuclear unit cell, based on the reported features of the parent TbM 2 B 2 C compounds. 18,19,21,22 The incommensurate structure of the pure Ni sample (x = 0) becomes, for x = 0.2 and 0.4, a collinear AFM mode with k =( 1 /2, 0, 1 /2), i.e., AFM along the a and c axes, and FM along the b axis; this structure is different from the a-axis modulated mode of TbNi 2 B 2 C, but similar to that of ErCo 2 B 2 C, 9 and NdNi 2 B 2 C.12 One should note that while the magnetic moment for x = 0.2 is | µ| = 7.6 µ B (thus very close to Table II, the Tb moments were taken to be polarized along the a axis.that for TbNi 2 B 2 C), for x = 0.4 it is | µ| = 3.7(2) µ B which is, surprisingly, less than half of the expected value. Such anomalous behavior is also evident in the thermodynamical properties.…”

“…10,12,17,18 Powder neutrondiffractograms were collected at the high resolution powder diffractometer D2B of the Institut Laue-Langevin (ILL), France (λ = 1.6Å, T = 1.5K and 30K), and were analyzed by the same Rietveld package. The diffractograms of the end members were not measured since these have already been determined.…”