Tailored VxOy Metal–Insulator-Transition Oxides for Temperature-Triggered Smart Insulation in Superconducting Coils
Abstract
Smart insulation is a turn-to-turn layer that insulates in normal operation and conducts only near a hot spot. It could combine the fast ramping of insulated coils with the passive energy dump of non-insulated coils. Metal-insulator transition (MIT) oxides are natural candidates, but the only one tested in a coil so far, V2O3, switches at 150-170 K, far above the 30-70 K window useful for REBCO magnets. We explore the vanadium-oxygen system to lower the transition. TGA redox processing produced multi-phase powders with an effective transition near 127 K, about 25 K below V2O3. Hydrothermal V3O7, hydrated or annealed, was far too resistive and showed no usable transition. V2O3-epoxy specimens provided a robust reference and an acceptance criterion. Cryogenic measurements revealed a reproducible thermal hysteresis, and the measured specific heat of V2O3 corrects earlier model inputs by close to two orders of magnitude. A first electro-thermal model reproduces current sharing through the smart-insulation layer. Doped V2O3 and V8O15 are identified as the next targets.
Related
- Preparation of a Laughlin-like fractional Chern insulator on a superconducting quantum processor
- Origins of microwave losses in superconducting circuits made with silicon-on-insulator substrates
- Vacancy-driven topological transition of a Chern insulator
- Dynamical transition in non-Hermitian Chern insulator
- Direct transition from a fractional Chern insulator to a topological superconductor
BibTeX
@misc{ortino2026tailored,
title = {{Tailored VxOy Metal–Insulator-Transition Oxides for Temperature-Triggered Smart Insulation in Superconducting Coils}},
author = {Mattia Ortino and Davide Uglietti and Andrea Testino and Nicola Casati and Alexander Steppke and Wiktoria Wnetkowska and Andrea Masi and Kamil Sedlak},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.16581},
eprint = {2610.16581},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05791897v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Tailored VxOy Metal–Insulator-Transition Oxides for Temperature-Triggered Smart Insulation in Superconducting Coils
AU - Mattia Ortino
AU - Davide Uglietti
AU - Andrea Testino
AU - Nicola Casati
AU - Alexander Steppke
AU - Wiktoria Wnetkowska
AU - Andrea Masi
AU - Kamil Sedlak
PY - 2026
DA - 2026/10/10
PB - HAL
DO - 10.48550/arxiv.2610.16581
UR - https://hal.science/hal-05791897v1
AB - Smart insulation is a turn-to-turn layer that insulates in normal operation and conducts only near a hot spot. It could combine the fast ramping of insulated coils with the passive energy dump of non-insulated coils. Metal-insulator transition (MIT) oxides are natural candidates, but the only one tested in a coil so far, V2O3, switches at 150-170 K, far above the 30-70 K window useful for REBCO magnets. We explore the vanadium-oxygen system to lower the transition. TGA redox processing produced multi-phase powders with an effective transition near 127 K, about 25 K below V2O3. Hydrothermal V3O7, hydrated or annealed, was far too resistive and showed no usable transition. V2O3-epoxy specimens provided a robust reference and an acceptance criterion. Cryogenic measurements revealed a reproducible thermal hysteresis, and the measured specific heat of V2O3 corrects earlier model inputs by close to two orders of magnitude. A first electro-thermal model reproduces current sharing through the smart-insulation layer. Doped V2O3 and V8O15 are identified as the next targets.
ER -