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M. B. Sreedhara

Publications and source records attributed to M. B. Sreedhara.

3 recordsLinked to original sources

Discovery of Superconductivity in a Bulk Moire Superlattice Material

Moire materials provide a versatile platform realizing emergent electronic states arising from enhanced correlation due to flat bands. A variety of phenomena including superconductivity, low dimensional ferromagnetism, Mott insulating phase, topological phenomena have been reported in such systems. To date, moire phenomena have been predominantly explored in artificially assembled low-dimensional van der Waals heterostructures, where relative twist and lattice alignment are controlled during device fabrication. Recently, intrinsically grown bulk moire crystals have emerged as a complementary materials platform, in which lattice mismatch between constituent layers generates a coherent moire superlattice throughout the bulk crystal. Here we report the evidence of bulk superconductivity in single crystals of a recently reported bulk Moire materials (Sr6TaS8)1+x(TaS2)8 under ambient pressure conditions. The material exhibits a superconducting transition at Tc = 2.5 K, evidenced consistently by electrical transport, magnetic susceptibility, and heat-capacity measurements on single-crystal and polycrystalline samples. Transport measurements reveal a pronounced anomaly near 270 K, suggestive of a charge-density-wave transition in this moire system. The observation of bulk superconductivity establishes superconductivity as an emergent phase in this intrinsically synthesized moire material and highlights bulk moire crystals as a promising platform for investigating correlated quantum phenomena beyond artificially assembled two-dimensional heterostructures.

cond-mat.supr-con↗

Growth of epitaxial ReS2 thin film by pulsed laser deposition

We present results on growth of large area epitaxial ReS2 thin film both on c plane sapphire substrate and MoS2 template by pulsed laser deposition (PLD). Films tend to grow with (0001) ReS2 perpendicular to (0001) Al2O3 and (0001) ReS2 perpendicular to (0001) MoS2 parallel to (0001) Al2O3 at deposition temperature below 300 deg C. Films are polycrystalline grown at temperature above 300 deg C. The smoothness and quality of the films are significantly improved when grown on MoS2 template compared to sapphire substrate. The results show that PLD is suitable to grow ReS2 epitaxial thin film over large area for practical device application.

cond-mat.mtrl-sci↗

Chemically stabilized epitaxial wurtzite-BN thin film

We report on the chemically stabilized epitaxial w-BN thin film grown on c-plane sapphire by pulsed laser deposition under slow kinetic condition. Traces of no other allotropes such as cubic (c) or hexagonal (h) BN phases are present. Sapphire substrate plays a significant role in stabilizing the metastable w-BN from h-BN target under unusual PLD growth condition involving low temperature and pressure and is explained based on density functional theory calculation. The hardness and the elastic modulus of the w-BN film are 37 & 339 GPa, respectively measured by indentation along <0001> direction. The results are extremely promising in advancing the microelectronic and mechanical tooling industry.

cond-mat.mtrl-sci↗