arXiv subjects

M. Lamba

Publications and source records attributed to M. Lamba.

4 recordsLinked to original sources

arXiv2026

Effects of Spin Fluctuation and Disorder on Topological States of Quasi 2D Ferromagnet Fe1/5CrTe2

We present a thorough magnetization and magneto-transport study of the diluted Fe-intercalated CrTe2 family member, Fe1/5CrTe2, a van der Waals ferromagnet. Fe1/5CrTe2 shows an elevated Curie transition temperature of 182 K in comparison to the Fe1/3CrTe2 composition, indicating the sensitive role of Fe concentration in modulating magnetic exchange interactions within the CrTe2 framework. The saturated magnetization exhibits a quadratic dependence with temperature, indicating the presence of long-wavelength spin fluctuations. Analysis of the temperature dependent resistivity reveals a dominant T3/2 contribution over the typical T2 behavior, signaling substantial coupling between conduction electrons and localized spins. The magnetoresistance shows a linear and non-saturating negative field dependency throughout a wide temperature range below TC, which is compatible with the increasing suppression of spin-disorder dispersion related to ferromagnetic spin fluctuations. A thorough analysis of the anomalous Hall effect (AHE) shows that extrinsic skew-scattering contribution, which is associated to Fe-related disorder, dominates the anomalous Hall response. The systematic separation of intrinsic and extrinsic components reveals that, over a wide temperature range, the intrinsic anomalous Hall conductivity scales linearly with the saturation magnetization, despite the substantial extrinsic dominant background. The linear behavior of intrinsic anomalous Hall conductivity with magnetization is in line with a long wavelength spin-fluctuation framework, where thermal spin disorder lowers net magnetization without significantly altering the underlying electronic structure. These findings reveal Fe1/5CrTe2 as a newly investigated van der Waals ferromagnet where spin fluctuations and disorder coexist with a well-defined intrinsic Berry-curvature contribution to the Hall response.

cond-mat.str-el↗

arXiv2025

Coexistence of Nodal and Nodeless Pairing Symmetry in Superconducting 6R-SnNbSe2

Majorana fermions, a fundamental idea to fault-tolerant quantum computing, can emerge in systems where superconductivity coexists with nontrivial band topology. One promising route to realizing such topological superconductors (TSCs) involves inducing superconductivity in topological materials, particularly in systems lacking inversion symmetry. In this study, we report the synthesis and detailed characterization of Sn-intercalated NbSe2, forming a new polytype, 6R-SnNbSe2. This compound crystallizes in the non-centrosymmetric space group R3m and exhibits bulk superconductivity below Tc around 4 K. Structural, electronic, and magnetic measurements confirm the emergence of a superconducting phase derived from Sn intercalation into the non-superconducting 3R-NbSe2. Temperature-dependent magnetic penetration depth and superfluid density measurements down to 1.5 K are performed using the tunnel diode oscillator technique. The findings suggest the mixing of nodal and nodeless superconductivity in 6R-SnNbSe2. Given the non-centrosymmetric nature of the crystal structure and the theoretical prediction of topological nodal-line features in SnNbSe2, it is an interesting candidate to investigate unconventional pairing mechanisms. Our findings highlight the potential of this material to host nontrivial superconducting states among the transition-metal dichalcogenides.

cond-mat.supr-con↗

arXiv2023

On the Experimental Evidence for Possible Superconductivity in LK99

The desire to create an energy efficient world is bound to be incomplete without the discovery of a room temperature superconductor at ambient pressure. A recent report on the room-temperature ambient-pressure superconductor has inspired scientists to study the Cu doped Lead apatite named as LK-99. Here, we have synthesized Cu doped LK-99 and Ni-doped LK-99 compounds and studied their temperature dependent transport and magnetization behavior. In spite of the presence of impurity phase Cu$_2$S, the temperature dependent resistance shows an insulating nature of the sample. The radio frequency penetration depth measurement unveils the absence of diamagnetic flux expulsion in this sample. The temperature dependent ac susceptibility measurements reveal the paramagnetic nature of the Ni doped LK-99.

cond-mat.supr-con↗

arXiv2023

Conventional Type-II Superconductivity in 2H-TaSeS

Superconductors based on transition metal dichalcogenides are of substantial current relevance, towards attaining topological superconductivity. Here we report a detailed study on the synthesis and electromagnetic characterization of high-quality single crystals of TaSeS. A superconducting transition is confirmed at 4.15K with coexisting charge density wave onset at 66K. The temperature dependence of RF penetration depth indicates s-wave characteristics in the weak coupling limit. A moderate electronic anisotropy is observed in upper critical fields with a value of 1.52. DFT calculations confirm the possibility of superconducting behavior of TaSeS and also suggest that the most stable structure belongs to P63mc space group. Negative values in phonon dispersion curves verify the possibility of co-existing CDW in 2H-TaSeS. Arrhenius plots show power law dependence of activation energy with respect to magnetic field. Overall all characteristics imply TaSeS to be a classic Type-II superconductor without any evidence for topological superconductivity.

cond-mat.supr-con↗