Publications
SC-1 etching of Nb and TiN thin films
A. Gutiérrez-Cruz, K. A. C. Rathnathilaka, J. M. Taskinen, T. Vaimala, K. Grigoras, H. Mishra, R. Upadhyay, J. Senior, and A. Ronzani.
arXiv preprint: https://doi.org/10.48550/arXiv.2605.28343
Dry etching techniques, ubiquitous in microelectronics fabrication, often result in challenging levels of undesired collateral plasma-induced damage. In this work, we demonstrate a wet etching alternative for the patterning of niobium (Nb) and titanium nitride (TiN) thin films … Read more
Detection of spin- and valley-polarized states in van der Waals materials via thermoelectric and non-reciprocal transport
O. A. Awoga, P. Virtanen, T. T. Heikkilä, S. Ilić
arXiv preprint: https://doi.org/10.48550/arXiv.2604.02427
We predict thermoelectric and current rectification effects in hybrid junctions formed by Ising superconductors and materials hosting valley-polarized states. Both effects originate from the interplay of intrinsic Ising spin-orbit coupling, spin-splitting from an exchange … Read more
Giant anomalous Josephson effect as a probe of spin texture in topological insulators
N. Hüttner, A. Costa, L. Tosi, M. Barth, W. Himmler, D. A. Kozlov, L. Golub, N. N. Mikhailov, K. Richter, D. Weiss, C. Strunk, & N. Paradiso
arXiv preprint: arXiv:2601.20410, 2026.
In this work, we explore the anomalous Josephson effect in junctions where the weak link is a HgTe nanowire. We observe a giant anomalous 𝜑0-shift of the current-phase relation … Read more
Josephson anomalous vortices
D. Crawford, S. Ili´c, P. Virtanen & T. T. Heikkilä
Physical Review B 113.2 (2026): L020503. https://doi.org/10.1103/nsdg-sn1b
We show that vortices with circulating current, related with odd-frequency triplet pairing, appear in Josephson junctions where the barrier is a weak ferromagnet with strong spin-orbit coupling. By symmetry analysis we show that there is an additional … Read more
Spontaneous supercurrents and vortex depinning in two-dimensional arrays of 𝜑0 Josephson junctions
S. Reinhardt, A. Penner, J. Berger, C. Baumgartner, S. Gronin, G. Gardner, T. Lindemann, M. Manfra, L. Glazman, F. von Oppen, N. Paradiso, & C. Strunk
Physical Review B 112.22, 224503 (2025) https://doi.org/10.1103/31zv-84hw
Two-dimensional arrays of ballistic Josephson junctions are important as model systems for synthetic quantum materials. Here, we investigate arrays of multiterminal junctions which exhibit a phase difference … Read more
Probing the flat-band limit of the superconducting proximity effect in twisted bilayer graphene Josephson junctions
A. Díez-Carlón, J. Díez-Mérida, P. Rout, D. Sedov, P. Virtanen, S. Banerje, R. P. S. Penttilä, P. Altpeter, K. Watanabe
Physical Review X 15.4, 041033 (2025) https://doi.org/10.1103/ccb4-tqxq
In this study, we probe proximity-induced superconductivity in Josephson junctions (JJs) formed between superconducting NbTiN electrodes and twisted bilayer graphene … Read more
Superconducting junctions with flat bands
P. Virtanen, R. P. S. Penttilä, P. Törmä, A. Díez-Carlón, D. K. Efetov, & T. T. Heikkilä
Physical Review B 112, L100502 (2025) https://doi.org/10.1103/7f1y-kjyl
We analyze the properties of flat-band superconductor junctions that behave differently from ordinary junctions containing only metals with Fermi surfaces. In particular, we show how in the tunneling limit the critical Josephson current between flat-band superconductors … Read more
Gate-tunable polarity inversions and three-fold rotation symmetry of the superconducting diode effect
W. F. Schiela, M. Mikalsen, D. Crawford, S. Ilić, W. M. Strickland, F. S. Bergeret, J. Shabani
arXiv preprint: https://doi.org/10.48550/arXiv.2504.21470
We study the superconducting diode effect in gated planar Josephson junctions fabricated on a superconductor-semiconductor heterostructure under an in-plane magnetic field. We observe two gate-driven inversions of the diode … Read more
Magnetoelectric effects in diffusive two-dimensional superconductors studied by the nonlinear 𝜎 model
P. Virtanen
Physical Review B 111.2, 024510 (2025) https://doi.org/10.1103/PhysRevB.111.024510
We describe a numerical approach to modeling magnetoelectric effects generated by spin-orbit coupling in inhomogeneous diffusive two-dimensional (2D) superconductors. It is based on direct … Read more
Superconducting diode effect in diffusive superconductors and Josephson junctions with Rashba spin-orbit coupling
S. Ilić, P. Virtanen, D. Crawford, T. T. Heikkilä, & F. S. Bergeret
Physical Review B 110, L140501 (2024) https://doi.org/10.1103/PhysRevB.110.L140501
We characterize the superconducting diode effect (SDE) in two-dimensional diffusive structures with Rashba spin-orbit coupling using the quasiclassical formalism. We consider both homogeneous superconductors … Read more
Wafer-scale CMOS-compatible graphene Josephson field-effect transistors
A. A. Generalov, K. L. Viisanen, J. Senior, B. R. Ferreira, J. Ma, M. Möttönen, M. Prunnila, & H. Bohuslavskyi
Applied Physics Letters 125, 012602 (2024) https://doi.org/10.1063/5.0203515
Electrostatically tunable Josephson field-effect transistors (JoFETs) are one of the most desired building blocks of quantum electronics. Applications of JoFETs range from parametric amplifiers and superconducting qubits to a variety of integrated superconducting circuits… Read more
Link between supercurrent diode and anomalous Josephson effect revealed by gate-controlled interferometry
S. Reinhardt, T. Ascherl, A. Costa, J. Berger, S. Gronin, G. C. Gardner, T. Lindemann, M. J. Manfra, J. Fabian, D. Kochan, C. Strunk, & N. Paradiso
Nature communications 15, 4413 (2024) https://doi.org/10.1038/s41467-024-48741-z
In Josephson diodes the asymmetry between positive and negative current branch of the current-phase relation leads to a polarity-dependent critical current and Josephson inductance … Read more
Nonreciprocal Josephson Linear Response
P. Virtanen, & T. T. Heikkilä
Physical Review Letters 132, 046002 (2024) https://doi.org/10.1103/PhysRevLett.132.046002
We consider the finite-frequency response of multiterminal Josephson junctions and show how nonreciprocity in them can show up at linear response, in contrast to the static Josephson diodes featuring nonlinear nonreciprocity. At finite frequencies, the response contains dynamic contributions to the Josephson admittance … Read more
Datasets and Repositories
Data archive of “SC-1 Etching of Niobium and Titanium Nitride Thin Films”
A. Gutiérrez-Cruz, K. A. C. Rathnathilaka, J. M. Taskinen, T. Vaimala, K. Grigoras, H. Mishra, R. Upadhyay, J. Senior, and A. Ronzani
Data archive of “Giant anomalous Josephson effect as a probe of spin texture in topological insulators”
N. Hüttner, A. Costa, L. Tosi, M. Barth, W. Himmler, D. A. Kozlov, L. Golub, N. N. Mikhailov, K. Richter, D. Weiss, C. Strunk, & N. Paradiso
Numerical modelling and computer algebra analysis for Josephson anomalous vortices
D. Crawford, S. Ili´c, P. Virtanen & T. T. Heikkilä
Data archive of “Spontaneous supercurrents and vortex depinning in two-dimensional arrays of φ0-junctions”
S. Reinhardt, A. Penner, J. Berger, C. Baumgartner, S. Gronin, G. Gardner, T. Lindemann, M. Manfra, L. Glazman, F. von Oppen, N. Paradiso & C. Strunk
Numerical modelling for “Superconducting junctions with flat bands”
P. Virtanen, R. P. S. Penttilä, P. Törmä, A. Díez-Carlón, D. K. Efetov, & T. T. Heikkilä
Open code repository for simulating hybrid diffusive weak links, JoFETs, and superconducting diodes
JYU Condensed Matter Theory, University of Jyväskylä
Data archive of “Link between supercurrent diode and anomalous Josephson effect revealed by gate-controlled interferometry
S. Reinhardt, T. Ascherl, A. Costa, J. Berger, S. Gronin, G. C. Gardner, T. Lindemann, M. J. Manfra, J. Fabian, D. Kochan, C. Strunk, & N. Paradiso
Code for manuscript “Nonreciprocal Josephson linear response
P. Virtanen, & T. T. Heikkilä