Deepesh Kalauni | Searcharxiv

arXiv2026

Development of a high-field pulsed magnet and optical fiber coupled cryostat system for magneto-photoluminescence measurements

This paper presents the development of a high field pulsed magnet system combined with an optical fiber-coupled low temperature cryostat for magneto-photoluminescence measurements. A novel aspect of our system is the use of electrolyte capacitors in a 75 kJ capacitor bank to drive the pulsed magnet, enabling the generation of high magnetic fields at a relatively low charging voltage (400 V). The zylon reinforced wire wound magnet coil achieves a maximum field strength of 35 tesla with a magnetic field rise time of 10 ms. The integrated cryostat was developed to meet the specific requirements of magneto-photoluminescence experiments using a 4 K helium closed-cycle cryocooler to provide a stable low-temperature environment down to 5 K.

physics.ins-det↗

arXiv2025

Evidence of Athermal Metastable Phase in a Halide Perovskite: Optically Tracked Thermal-Breach Memory

Halide perovskite materials have been extensively studied in the last decade because of their impressive optoelectronic properties. However, their one characteristic that is uncommon for semiconductors is that many undergo thermally induced structural phase transitions. The transition is hysteretic, with the hysteresis window marking the boundary of the metastable phase. We have discovered that in methylammonium lead iodide, this hysteretic metastable phase is athermal, meaning it shows almost no temporal phase evolution under isothermal conditions. We also show that a large number of distinguishable metastable states can be prepared following different thermal pathways. Furthermore, under a reversible thermal perturbation, the states in the metastable phase either show return-point memory or undergo a systematic nonrecoverable phase evolution, depending on the thermal history and the sign of the temperature perturbation. Since the phase fraction can be probed with extreme sensitivity via luminescence, we have an optically retrievable memory that reliably records any breach in temperature stability. Such thermal-breach memory in athermal martensites, of which there are numerous examples, may be useful for tagging packages requiring strict temperature control during transportation or preservation.

cond-mat.mtrl-sci↗