Magnetic and transport anomalies and large magnetocaloric effect in cubic R4PtAl (R = Ho and Er)

Kartik K. Iyer; Sudhindra Rayaprol; Ram Kumar; Shidaling Matteppanavar; Suneel Dodamani; Kalobaran Maiti; Echur V. Sampathkumaran

arXiv · 2304.10121

Magnetic and transport anomalies and large magnetocaloric effect in cubic R4PtAl (R = Ho and Er)

Kartik K. Iyer·Sudhindra Rayaprol·Ram Kumar·Shidaling Matteppanavar·Suneel Dodamani·Kalobaran Maiti·Echur V. Sampathkumaran

View original source ↗Read source document ↗Export metadata ↓

Abstract

We report the electronic properties of R4PtAl (R = Ho, and Er), which contains 3 sites for R, by the measurements of magnetization (ac and dc), heat-capacity, transport, and magnetoresistance (MR). Dc magnetization data reveal antiferromagnetic order below 19 K and 12 K in Ho and Er compounds, respectively. Additional features observed at lower temperatures (12 K for Ho4PtAl and 5 K for Er4PtAl) are akin to cluster spin-glass phase. Resistivity data exhibit a weak minimum at a temperature marginally higher than their respective N\'eel temperature (T_N) which is unusual for such rare-earths with well localized 4f states. Isothermal magnetization and magnetoresistance data well below T_N exhibit signatures of a subtle field-induced magnetic transition for a small magnetic field (less than 10 kOe). Notably, the isothermal entropy change at T_N has the largest peak value within this rare-earth family; for a field change from zero to 50 kOe, the entropy change is about 14.5 J/kg K (Ho4PtAl) and 21.5 J/kg K (Er4PtAl) suggesting a role of anisotropy of 4f orbital in determining this large value. The results provide some clues for the advancement of the field of magnetocaloric effect. The magnetocaloric property of Er4PtAl is nonhysteretic meeting a challenge to find materials with reversible magnetocaloric effect.

Explore related subjects

cond-mat.str-el cond-mat.mtrl-sci

Keep this discovery

BibTeX RIS

Kartik K. Iyer, Sudhindra Rayaprol, Ram Kumar, Shidaling Matteppanavar, Suneel Dodamani, Kalobaran Maiti, Echur V. Sampathkumaran. 2023-04-20. Magnetic and transport anomalies and large magnetocaloric effect in cubic R4PtAl (R = Ho and Er). https://arxiv.org/abs/2304.10121

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Competing Interlayer Loop Currents and Superconductivity in the Bilayer $t$-$J_\perp$-$V$ Model

The recent discovery of high-$T_c$ superconductivity in pressurized and thin-film bilayer nickelates, featuring a strong interlayer exchange coupling, and their potential similarities with cuprate superconductors, has made this a very active topic in condensed matter physics. In the present paper we study the strongly correlated one-orbital ($d_{x^2-y^2}$) bilayer $t$-$J_\perp$-$V$ model for nickelates, where $V$ denotes the Coulomb interactions, using a controlled large-$N$ expansion at and beyond the mean-field level. Focusing on the out-of-plane spin exchange interaction ($J_\perp$), we find that it triggers both out-of-plane $s$-wave superconductivity and an out-of-plane bond-order phase ($z$-BOP) instability. The $z$-BOP gives rise to a complex $z$-axis hopping dominated by its imaginary component, which drives out-of-plane currents and induces in-plane ones, spontaneously forming on the vertical plaquettes a loop-current state that breaks time-reversal symmetry. Competition between this loop-current phase and superconductivity yields a dome-shaped superconducting region, with optimal superconductivity occurring near the $z$-BOP quantum critical point. The resulting phase diagram features a pure loop-current region, a low-doping coexistence phase, a pure superconducting state at higher doping, and a correlated metallic state.

cond-mat.str-el↗

arXiv2026

Optically induced metallic state with persistent monoclinic symmetry in NdNiO$_3$

Understanding whether electronic and structural order remain coupled under nonequilibrium conditions is a central challenge in correlated materials. Here, we simultaneously track metallicity and symmetry across the photoinduced insulator-to-metal transition in NdNiO$_3$ using time-resolved optical reflectivity and symmetry-sensitive second-harmonic generation. We find that metallic reflectivity emerges at significantly lower excitation fluence than restoration of the orthorhombic high-temperature symmetry. As a result, optical excitation stabilizes a metastable state that combines the reflectivity of the metallic phase with the monoclinic symmetry of the insulating phase, revealing an optically induced monoclinic metal. Only at substantially higher fluences does the symmetry fully recover to that of the high-temperature phase. These results demonstrate a nonequilibrium decoupling of metallicity and structural symmetry and establish simultaneous multiprobe spectroscopy as a powerful approach for identifying emergent phases in correlated materials.

cond-mat.str-el↗

arXiv2026

Instabilities in self-consistent diagrammatic approaches and how to cure them

While self-consistent diagrammatic approaches are widely used to compute the physical properties of correlated quantum materials, their applicability may get severely hindered precisely in the parameter regions, where the most exciting physics is observed. One of the major issues, referred to as "misleading convergence", is the tendency of iterative schemes to converge to unphysical fixed points for intermediate-to-strong electronic interactions, regardless of numerical accuracy of the computation. Here, we explicitly verify that the origin of this problem in several established self-consistent many-electron approaches, defined in the general diagrammatic framework of the boson-exchange formalism, resides exclusively in the stability condition of the respective iteration schemes, and not in an intrinsic breakdown of their self-consistent diagrammatic description. This insight enables a simple and general remedy, as recently proposed in Phys. Rev. Lett. 137, 016502 (2026): The redefinition of the iterative procedure, by inverting the unstable eigendirections of the Jacobian associated to the fixed point of the self-consistent algorithm. We illustrate the successful outcome of this procedure by means of systematic calculations performed on testbed, exactly solvable, models. Our results demonstrate that the physical fixed point of the diagrammatic schemes we considered can be stabilized, de facto, across the entire parameter range, including the most challenging nonperturbative/strong-coupling regimes.

cond-mat.str-el↗