arXiv subjects

Hicham Moutaabbid

Publications and source records attributed to Hicham Moutaabbid.

4 recordsLinked to original sources

arXiv2026

A metallic CrS$_2$ phase bridging the gap between two- and three-dimensional dichalcogenides

We report on the high-pressure synthesis of a CrS$_2$ phase in the form of single-crystalline nanorods. A structural refinement of Precession Electron Diffraction Tomography data confirms the nominal CrS$_2$ composition and unveils a ladder-type structure formed by portions of 1T-type CrS$_2$ layers characteristic of two-dimensional (2D) dichalcogenides connected by chains of edge-sharing CrS$_6$ octahedra characteristic of 3D dichalcogenides with marcasite structure. Ab initio density functional theory calculations of the relaxed structure confirm the stability of this structure and indicate a strong overlap of the 3d states of Cr with the 3p states of S, thus suggesting strong covalent Cr-S bonds and metallic behavior. Electrical resistivity, $\varrho$, measurements on single nanorods confirm this behavior and yield $\varrho \sim 2-20$ m$Ω$ cm at 4 K. The proposed ladder-like structure of CrS$_2$ forms open channels along the chain direction, which may be suitable for ionic conduction.

cond-mat.mtrl-sci↗

arXiv2024

Evidence of a Kondo lattice quantum critical point and of non-Fermi liquid behavior in the intercalated layered system V$_{5}$S$_{8}$

By means of a specific heat, susceptibility and high-pressure electrical resistivity study, we show that the local magnetic moments of the intercalated V ions in V$_{5}$S$_{8}$ realize a prototype of Kondo lattice system, where an antiferromagnetic order of the moments coexists with a Fermi liquid in the VS$_{2}$ layers with intermediate heavy Fermion properties. The antiferromagnetic order and the Fermi-liquid behavior are simultaneously suppressed at a critical pressure, $P_c =10$ GPa, signature of a quantum critical point, which supports a Kondo lattice scenario and raises the question whether, in the paramagnetic phase at higher pressures, the heavy quasiparticles survive or form a non-Fermi liquid phase governed by the Kondo interaction.

cond-mat.str-el↗

arXiv2018

Modulated magnetic structure in 57Fe doped orthorhombic YbMnO3: a Mössbauer study

In the orthorhombic manganites o-RMnO3, where R is a heavy rare earth (R = Gd-Yb), the Mn3+ sublattice is known to undergo two magnetic transitions. The low temperature phase has an antiferromagnetic structure (collinear or elliptical), which has been well characterized by neutron diffraction in most of these compounds. The intermediate phase, occurring in a narrow temperature range (a few K), is documented for R = Gd-Ho as a collinear modulated structure, incommensurate with the lattice spacings. We report here on a 57Fe Mössbauer study of 2% 57Fe doped o-YbMnO3, where the spin only Fe3+ ion plays the role of a magnetic probe. From the analysis of the shape of the magnetic hyperfine Mössbauer spectra, we show that the magnetic structure of the intermediate phase in o-YbMnO3 (38.0 K < T < 41.5 K) is also modulated and incommensurate.

cond-mat.str-el↗

arXiv2016

Phase boundary between Na-Si clathrates of structures I and II at high pressures and high temperatures

Understanding the covalent clathrate formation is a crucial point for the design of new superhard materials with intrinsic coupling of superhardness and metallic conductivity. Silicon clathrates have the archetype structures that can serve an existant model compounds for superhard clathrate frameworks "Si-B", "Si-C", "B-C" and "C" with intercalated atoms (e.g. alkali metals or even halogenes) that can assure the metalic properties. Here we report the in situ and ex situ studies of high-pressure formation and stability of clathrates Na8Si46 (structure I) and Na24+xSi136 (structure II). Experiments have been performed using standard Paris-Edinburgh cells (opposite anvils) up to 6 GPa and 1500 K. We have established that chemical interactions in Na-Si system and transition between two structures of clathrates occur at temperatures below silicon melting. The strong sensitivity of crystallization products to the sodium concentration have been observed. A tentative diagram of clathrate transformations has been proposed. At least up to ~6 GPa, Na24+xSi136 (structure II) is stable at lower temperatures as compared to Na8Si46 (structure I).

cond-mat.mtrl-sci↗