arXiv subjects

Md Azimul Haque

Publications and source records attributed to Md Azimul Haque.

4 recordsLinked to original sources

arXiv2025

Chirality-induced magnetoresistance in hybrid organic-inorganic perovskite semiconductors

The combination of semiconducting properties and synthetically tunable chirality in chiral metal halide semiconductors (CMHS) offer a compelling platform for room temperature control over electronic spin properties, leveraging effects such as chirality-induced spin selectivity (CISS) for the development of new opto-spintronic functionalities. We report room-temperature CISS-induced magnetoresistance (CISS-MR) exceeding 100% for spin valves in a configuration consisting of a ferromagnet (FM), tunneling barrier, and CMHS. The high CISS-MR is attributed to interfacial spin-selective tunneling barrier induced by the chirality, which can produce current dissymmetry factors that surpass the limit imposed by the Julli\`ere model governed by the intrinsic spin polarization of the adjacent FM contact. The CISS-MR exhibits a strong dependence on the CMHS composition, revealing a structure-property relationship between CISS and structural chirality. The observed exceptionally large tunneling MR response differentiates from a subtle anisotropic MR arising from the proximity effect at the FM/CMHS interface in the absence of a tunneling barrier. Our study provides insights into charge-to-spin interconversion in chiral semiconductors, offering materials design principles to control and enhance CISS response and utilize it in functional platforms.

cond-mat.mtrl-sci↗

arXiv2023

Tunable Magnon-Photon Coupling by Magnon Band Gap in a Layered Hybrid Perovskite Antiferromagnet

Tunability of coherent coupling between fundamental excitations is an important prerequisite for expanding their functionality in hybrid quantum systems. In hybrid magnonics, the dipolar interaction between magnon and photon usually persists and cannot be switched off. Here, we demonstrate this capability by coupling a superconducting resonator to a layered hybrid perovskite antiferromagnet, which exhibits a magnon band gap due to its intrinsic Dzyaloshinskii-Moriya interaction. The pronounced temperature sensitivity of the magnon band gap location allows us to set the photon mode within the gap and to disable magnon-photon hybridization. When the resonator mode falls into the magnon band gap, the resonator damping rate increases due to the nonzero coupling to the detuned magnon mode. This phenomena can be used to quantify the magnon band gap using an analytical model. Our work brings new opportunities in controlling coherent information processing with quantum properties in complex magnetic materials.

cond-mat.mtrl-sci↗

arXiv2023

Inorganic Tin Perovskites with Tunable Conductivity Enabled by Organic Modifiers

Achieving control over the transport properties of charge-carriers is a crucial aspect of realizing high-performance electronic materials. In metal-halide perovskites, which offer convenient manufacturing traits and tunability for certain optoelectronic applications, this is challenging: The perovskite structure itself, poses fundamental limits to maximum dopant incorporation. Here, we demonstrate an organic modifier incorporation strategy capable of modulating the electronic density of states in halide tin perovskites without altering the perovskite lattice, in a similar fashion to substitutional doping in traditional semiconductors. By incorporating organic small molecules and conjugated polymers into cesium tin iodide (CsSnI3) perovskites, we achieve carrier density tunability over 2.7 decades, transition from a semiconducting to a metallic nature, and high electrical conductivity exceeding 200 S/cm. We leverage these tunable and enhanced electronic properties to achieve a thin-film, lead free, thermoelectric material with a near room-temperature figure-of-merit (ZT) of 0.21, the highest amongst all halide perovskite thermoelectrics. Our strategy provides an additional degree of freedom in the design of halide perovskites for optoelectronic and energy applications.

physics.app-ph↗

arXiv2023

Closed-loop Error Correction Learning Accelerates Experimental Discovery of Thermoelectric Materials

The exploration of thermoelectric materials is challenging considering the large materials space, combined with added exponential degrees of freedom coming from doping and the diversity of synthetic pathways. Here we seek to incorporate historical data and update and refine it using experimental feedback by employing error-correction learning (ECL). We thus learn from prior datasets and then adapt the model to differences in synthesis and characterization that are otherwise difficult to parameterize. We then apply this strategy to discovering thermoelectric materials where we prioritize synthesis at temperatures < 300°C. We document a previously unreported chemical family of thermoelectric materials, PbSe:SnSb, finding that the best candidate in this chemical family, 2 wt% SnSb doped PbSe, exhibits a power factor more than 2x that of PbSe. Our investigations show that our closed-loop experimentation strategy reduces the required number of experiments to find an optimized material by as much as 3x compared to high-throughput searches powered by state-of-the-art machine learning models. We also observe that this improvement is dependent on the accuracy of prior in a manner that exhibits diminishing returns, and after a certain accuracy is reached, it is factors associated with experimental pathways that dictate the trends.

cond-mat.mtrl-sci↗