ERC consolidator grant: Electronic Order, Magnetism, and Unconventional Superconductivity probed in Real-Space - MARS

Dr. Christian Hess

Scope of the project

The interrelation of electronic order with antiferromagnetism and superconductivity is a vital question for rationalizing the physics of all classes of unconventional superconductors. Typically, such electronic ordering phases, which recently have been dubbed intertwined phases, are ubiquitously found at the crossover between ostensibly competing antiferromagnetic and superconducting states. Only rarely the electronic order is sufficiently long-range correlated to render it susceptible for diffraction techniques. Instead, it usually requires a local probe to detect it experimentally. It is clear, however, that such a probe must provide sensitivity at the same time to electronic order, superconductivity, and static magnetism for a full characterization of the intertwined phases, aiming at clarifying the interrelation between these ordering phenomena. The only experimental technique which is capable of fulfilling these requirements simultaneously is spin-polarized scanning tunnelling microscopy (SP-STM), which to the best of our knowledge, has never been applied to this intriguing problem in a systematic way, despite the apparent mandatory necessity.

In this project, in collaboration with the IFW Research Technology Department we have been building from scratch a new type of low-temperature scanning tunneling microscope which operates at 30mK with a vector magnetic field (9 Tesla vertical and 4 Tesla horizontal). Today, the instrument has been completed to a stage where high resolution measurements at base temperature can routinely be performed. Once completed, we can already say today that this novel instrument has the potential to deliver novel insight into the physics of novel quantum materials with very high spatial and energetic resolution.

In addition to this constructive work, numerous experimental studies mainly using scanning tunneling spectroscopy but also transport experiments have been performed on several types of unconventional superconductors and closely related correlated electron systems.

Duration: September 2015 - August 2020

Project-related Publications

Polymorphic PtBi2 – candidate for topological superconductivity,
G. Shipunov, I. Kovalchuk, B. R. Piening, V. Labracherie, A. Veyrat, J. Dufouleur, S. Shokri, F. Caglieris, C. Hess, D. V. Efremov, B. Büchner, S. Aswartham,

Percolative Mott insulator-metal transition in doped Sr2IrO4,
Z. Sun, J. M. Guevara, S. Sykora, E. M. Pärschke, J. van den Brink, K. Manna, A. Maljuk, S. Wurmehl, B. Büchner, C. Hess,

Evolution of the nematic susceptibility in LaFe1-xCoxAsO,
X. Hong, F. Caglieris, R. Kappenberger, S. Wurmehl, S. Aswartham, F. Scaravaggi, P. Lepucki, A. U. B. Wolter, H. Grafe, B. Büchner, C. Hess,
Phys. Rev. Lett. 125, 067001 (2020)

Substrate-Independent Magnetic Bistability in Monolayers of the Single-Molecule Magnet Dy2ScN@C80 on Metals and Insulators,
D. S. Krylov, S. Schimmel, V. Dubrovin, F. Liu, T. T. N. Nguyen, L. Spree, C.-H. Chen, G. Velkos, C. Bulbucan, R. Westerström, M. Studniarek, J. Dreiser, C. Hess, B. Büchner, S. M. Avdoshenko, A. A. Popov,
Angewandte Chemie 59, 5756 (2020)

Mg3(Bi,Sb)2 single crystals towards high thermoelectric performance,
Y. Pan, M. Yao, X. Hong, Y. Zhu, F. Fan, K. Imasato, Y. He, C. Hess, J. Fink, J. Yang, B. Büchner, C. Fu, G. J. Snyder, C. Felser,
Energy Environ. Sci. 13, 1717 (2020)

Incommensurate magnet iron monophosphide FeP: Crystal growth and characterization I. O. Chernyavskii, S. E. Nikitin, Y. A. Onykiienko, D. S. Inosov, Q. Stahl, J. Geck, X. C. Hong, C. Hess, S. Gass, A. U. B. Wolter, D. Wolf, A. Lubk, D. V. Efremov, F. Yokaichiya, S. Aswartham, B. Büchner, I. V. Morozov,
Phys. Rev. Materials 4, 083403 (2020)

Disorder-induced coupling of Weyl nodes in WTe2,
S. Sykora, J. Schoop, L. Graf, G. Shipunov, I. V. Morozov, S. Aswartham, B. Büchner, C. Hess, R. Giraud, J. Dufouleur,
Phys. Rev. Research 2, 033041 (2020)

Orbital-driven elasto-Seebeck and elasto-Nernst effects in 1111 iron based superconductors,
F. Caglieris, C. Wuttke, X. Hong, S. Sykora, R. Kappenberger, S. Aswartham, S. Wurmehl, B. Büchner, C. Hess,

Berry curvature unravelled by the anomalous Nernst effect in MnGe3,
C. Wuttke, F. Caglieris, S. Sykora, F. Scaravaggi, A. U. B. Wolter, K. Manna, V. Süss, C. Shekhar, C. Felser, B. Büchner, C. Hess,
Phys. Rev. B 100, 085111 (2019)

Spectroscopic evidence of nematic fluctuations in LiFeAs,
Z. Sun, P. K. Nag, S. Sykora, J. M. Guevara, S. Hoffmann, C. Salazar, T. Hänke, R. Kappenberger, S. Wurmehl, B. Büchner, C. Hess,
Phys. Rev. B 100, 024506 (2019)

Spin-polaron ladder spectrum of the spin-orbit-induced Mott insulator Sr2IrO4 probed by scanning tunneling spectroscopy,
J. M. Guevara, Z. Sun, E. M. Pärschke, S. Sykora, K. Manna, J. Schoop, A. Maljuk, S. Wurmehl, J. van den Brink, B. Büchner, C. Hess,
Phys. Rev. B 99, 121114(R) (2019)

An ultra-high vacuum scanning tunneling microscope operating at sub-Kelvin temperatures and high magnetic fields for spin-resolved measurements,
C. Salazar, D. Baumann, T. Hänke, M. Scheffler, T. Kühne, M. Kaiser, R. Voigtländer, D. Lindackers, B. Büchner, C. Hess,
Rev. Sci. Inst. 89, 065104 (2018)

Adsorption characteristics of Er3N@C80 on W(110) and Au(111) studied via scanning tunneling microscopy and spectroscopy,
S. Schimmel, Z. Sun, D. Baumann, D. Krylov, N. Samoylova, A. Popov, B. Büchner, C. Hess,
Beilstein J. Nanotechnol. 8, 1127 (2017)

Defect states in LiFeAs as seen by low temperature scanning tunneling microscopy and spectroscopy,
R. Schlegel, P. K. Nag, D. Baumann, R. Beck, S. Wurmehl, B. Büchner, C. Hess
Phys. Status Solidi B, 254, 1600159 (2017)

Two distinct superconducting phases in LiFeAs,
P. K. Nag, R. Schlegel, D. Baumann, H.-J. Grafe, R. Beck, S. Wurmehl, B. Büchner, C. Hess,
Scientific Reports 6, 27926 (2016)


Principal Investigator: Dr. Christian Hess

Former Team Members
Dr. Dmitriy Efremov
Dr. Mostafa Enayat
Matthias Gillig
Sven Hoffmann
Dr. Xiaochen Hong
Tim Kühne
Dr. Pranab Kumar Nag
Vladislav Nagorkin
Thi Thuy Nhung Nguyen
Jose Maria Guevara Parra
Himanshu Phirke
Dr. Christopher Reiche
Dr. Christian David Salazar Enriquez
Sebastian Schimmel
Dr. Zhixiang Sun
Dr. Steffen Sykora
Christoph Wuttke


This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 647276-MARS-ERC-2014-CoG).