arXiv subjects

Marc de Boissieu

Publications and source records attributed to Marc de Boissieu.

3 recordsLinked to original sources

arXiv2026

Breakdown of Universal Whirling Order in a Heisenberg Tsai-Type Approximant

Noncoplanar whirling magnetic order has recently been proposed as a universal magnetic state in non-Heisenberg Tsai-type quasicrystal approximants. Here, X-ray resonant magnetic scattering measurements on Heisenberg and non-Heisenberg Au-Al-R (R = Gd, Tb) 1/1 approximants reveal a clear breakdown of this universality in the Heisenberg limit. While the non-Heisenberg Au-Al-Tb system is well described by the previously identified whirling magnetic structure, the Heisenberg Au-Al-Gd counterpart exhibits qualitatively different azimuthal-angle dependences that are incompatible with the universal whirling-order model. Despite nearly identical crystal structures and comparable magnetic energy scales, the two systems stabilize distinct antiferromagnetic ground states with the same propagation vector k = (1, 0, 0), demonstrating that the apparent universality of whirling order is not a consequence of Tsai-cluster geometry alone but requires spin anisotropy. These results further reveal the emergence of a competing manifold of nearly degenerate magnetic states in the Heisenberg limit.

cond-mat.str-el↗

arXiv2026

Atomic structure and formation mechanism of a newly discovered charge density wave in the m=2 monophosphate tungsten bronze

The $m$=2 member of the monophosphate tungsten bronze family has been considered the only one in the family without an electronic instability at low temperature. In this paper, we report the discovery of a charge density wave phase in this compound, with a transition temperature of 290 K and an incommensurate modulation vector \textbf{q}=0.245\textbf{b*}+ $\upxi$\textbf{c*}. The presence of this new phase is confirmed by diffraction and resistivity measurements. Pre-transitional dynamics are investigated using diffuse and inelastic x-ray scattering, revealing a clear Kohn anomaly. We analyze both structural and electronic contributions to the phase transition, providing a comprehensive picture of the mechanism driving this newly identified instability.

cond-mat.str-el↗

arXiv2018

Interpretation of some Yb-based valence-fluctuating crystals as approximants to a dodecagonal quasicrystal

The hexagonal ZrNiAl-type (space group: P-62m) and the tetragonal Mo2FeB2-type (space group: P4/mbm) structures, which are frequently formed in the same Yb-based alloys and exhibit physical properties related to valence-fluctuation, can be regarded as approximants of a hypothetical dodecagonal quasicrystal. Using Pd-Sn-Yb system as an example, a model of quasicrystal structure has been constructed, of which 5-dimensional crystal (space group: P12/mmm, aDD=5.66 Å and c=3.72 Å) consists of four types of acceptance regions located at the following crystallographic sites; Yb [00000], Pd[1/3 0 1/3 0 1/2], Pd[1/3 1/3 1/3 1/3 0] and Sn[1/2 00 1/2 1/2]. In the 3-dimensional space, the quasicrystal is composed of three types of columns, of which c-projections correspond to a square, an equilateral triangle and a 3-fold hexagon. They are fragments of two known crystals, the hexagonal α-YbPdSn and the tetragonal Yb2Pd2Sn structures. The model of the hypothetical quasicrystal may be applicable as a platform to treat in a unified manner the heavy fermion properties in the two types of Yb-based crystals.

cond-mat.str-el↗