Fingerprints of Majorana modes beyond the zero-bias conductance peak

Satoshi Ikegaya

The unambiguous detection of Majorana bound states (MBSs) in topological superconductors has been a central topic of condensed matter physics for recent years. So far, the presence of MBSs was demonstrated experimentally in a number of topologically nontrivial superconducting systems. In this connection, clear evidences of Majorana bound states are only obtained by the detection of zero-bias conductance peaks in tunneling transport measurements. In recent years, it became clear that various additional signatures of Majorana modes need to be investigated in order to complete our understanding.
In our presentation, we summarize two unambiguous fingerprints which can act as a ‘smoking gun’evidence. First we study the anomalous nonlocal conductance due to chiral Majorana edge states in a superconductor/ferromagnet hybrid as shown in Fig. 1(a). We obtain the important result that the chiral nature of the Majorana edge states causes an anomalously long-range and chirality-sensitive nonlocal transport in this device. This, in turn, enables us to identify conclusively the moving direction and further properties of the chiral Majorana edge states [1]. Secondly, we propose a novel experiment for achieving the first experimental observation of the anomalous proximity effect caused by Majorana bound states. In particular, we discuss the differential conductance of a semiconductor/superconductor hybrid as shown in Fig. 1(b), which contains a planar topological Josephson junction realized in recent experiments. The conductance spectrum changes drastically through the topological phase transition because the Majorana bound state appearing only in the topologically nontrivial phase can penetrate into the dirty normal segment and form the resonant transmission channel there [2]. In general, our results allow contrasting singlet and triplet superconductivity employing properties of Majorana modes beyond zero bias peaks.

[1] S. Ikegaya, Y. Asano, and D. Manske, Phys. Rev. Lett. 123, 207002 (2019)
[2] S. Ikegaya, S. Tamura, D. Manske, and Y. Tanaka, arXiv: 2007.12888 (2020)

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Odd-frequency pairing in topological superconductors

Yukio Tanaka

It is known that odd-frequency pairing ubiquitously presents in superconductor junctions [1]. Especially, in the presence of zero energy surface Andreev bound state (ZESABS) realized in topological superconductors, the odd-frequency pairing is amplified near the surface or interface. One of the remarkable property generated by odd-frequency pairing is anomalous proximity effect in diffusive normal metal (DN) / superconductor junction where quasiparticle density of states in DN has a zero energy peak (ZEP) of LDOS due to the penetration of odd-frequency spin-triplet s-wave pairing [2,3]. It has been shown that proximity coupled nano-wire junction [4] is an idealistic system to study anomalous proximity effect due to odd-frequency triplet-s wave pairing [5].
We have further clarified the relation between induced odd-frequency pairing and the bulk quantity defined by Green’s function[6]. Odd-frequency Cooper pairs with chiral symmetry emerging at the edges are a useful physical quantity. We have shown that the odd-frequency Cooper pair amplitudes can be expressed by a winding number extended to a nonzero frequency and can be evaluated from the spectral features of the bulk. We have found that the odd-frequency Cooper pair amplitudes are classified into two categories: the amplitudes in the first category have the singular functional form proportional to 1/z (where z is a complex frequency) that reflects the presence of ZESABS, whereas the amplitudes in the second category have the regular form proportional to z.
Recently, we have found that the presence of ZESABS generates new type of thermopower.
We have shown that the thermoelectric effect in ferromagnet / superconductor junctions can be entirely dominated by ingap Andreev reflection processes. Consequently, the electric current from a temperature bias changes sign in the presence of ZESABS and resulting odd-frequency pairing [7].

[1]Y. Tanaka, M. Sato and N. Nagaosa, J. Phys. Soc. Jpn. 81 011013 (2012)
[2]Y. Tanaka and A.A. Golubov, Phys. Rev. Lett. 98 037003 (2007)
[3]Y. Tanaka, A.A. Golubov, S. Kashiwaya, and M. Ueda, Phys. Rev. Lett. 99 037005 (2007); Y. Tanaka, Y. Tanuma, and A. A. Golubov, Phys. Rev. B 96 054552 (2007)
[4]Y. Tanaka and S. Kashiwaya, Phys. Rev. B 70 012507 (2004)
[5]R. M. Lutchyn, J. D. Sau, and S. Das Sarma, Phys. Rev. Lett. 105, 077001 (2010), Y. Oreg, G. Refael, and F. von Oppen, Phys. Rev. Lett. 105, 177002 (2010)
[6]Y. Asano and Y. Tanaka, Phys. Rev. B 87 104513 (2013)
[7]S. Ta mura, S. Hoshino and Y. Tanaka, Phys. Rev. B 99 , 184512 (2019)
[8]T. Savander , S. Tamura, C. Flindt, Y. Tanaka and P. Burset , arXiv: 2008.00849

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Propagation and interference of d-wave superconducting pairs in graphene

Javier Villegas

Following earlier work in which we demonstrated the Klein-like tunneling of d-wave superconducting paints intro graphene [1], here we present experiments that show the longrange preparation of d-wave correlations in that material. For this, we fabricated devices that behave as a proximitized Fabry-Pérot cavitiy, where d-wave Andreev pairs interferences are produced. The interferences manifest themselves in series of pronounced conductance oscillations analogous to those produced by De Gennes-Saint James resonances in conventional superconductor/metal junctions. Their observation imply that the d-wave Andreev pairs propagate over distances of a few hundred nm in the CVD graphene used for the experiments [2]. We will end up by discussing ongoing experiments in applied magnetic field, which also produces an intriguing series of conductance oscillations in the superconducting state of the junctions.

[1] D. Perconte, F. A. Cuellar, C. Moreau-luchaire, M. Piquemal-Banci, R. Galceran, P. R. Kidambi, M.-B. Martin, S. Hofmann, R. Bernard, B. Dlubak, P. Seneor, and J. E. Villegas, Nat. Phys. 14, 25 (2018)
[2] D. Perconte, K. Seurre, V. Humbert, C. Ulysse, A. Sander, J. Trastoy, V. Zatko, F. Godel, P. R. Kidambi, S. Hofmann, X. P. Zhang, D. Bercioux, F. S. Bergeret, B. Dlubak, P. Seneor, and J. E. Villegas, Phys. Rev. Lett. 125, 87002 (2020)

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Poster Session


Poster 13 Mátyás Kocsis Department of Physics, BUTE Tuning the nonreciprocal resistance of BiTeBr
Poster 14 Kinga Lasek University of South Florida Molecular Beam Epitaxy of Self-Intercalated Transition Metal Tellurides
Poster 15 Soo Yeon Lim Sogang University Thickness dependent magnetic transition of MnPS3
Poster 16 Mingzu Liu The Pennsylvania State University Tunable RT FM in 1L V-WS2 & V-WSe2 via CVD
Poster 17 Francisco Munoz Universidad de Chile Magnon Hall Effect in CrI3-based vdW systems
Poster 18 Tianxiao Nie Beihang University 2D ferromagnetic materials above room temperature
Poster 19 Sergey Nikolaev Tokyo Institute of Technology Realistic modelling of monolayer NbS2 and NbSe2
Poster 20 Armando Pezo Federal University of ABC TMDC/Graphene an ab initio study
Poster 21 Charis Quay UniversitÈ Paris-Saclay Tunneling spectroscopy of few-monolayer NbSe2
Poster 22 Akhil Rajan University of St Andrews Morphology control of monolayer transition metal dichalcogenides by MBE
Poster 23 Patrick Reiser University of Basel Scanning NV Magnetometry of 2D Magnetism


Intrinsic 2D-XY ferromagnetism in a van der Waals monolayer

Amilcar Bedoya-Pinto

Long before the recent fascination with two-dimensional materials, the critical behaviour and universality scaling of phase transitions in low-dimensional systems has been a topic of great interest. Recent experiments on layered magnetic systems show that a sizable out-of-plane magnetic anisotropy is able to stabilize 2D long-range ferromagnetic order, as demonstrated in CrI3, CrBr3, Fe3GeTe2 and Cr2Ge2Te6 [1], while a spontaneous magnetic ordering has remained elusive for an in-plane 2D magnetic system in the monolayer limit. Here, we construct a nearly ideal easy-plane system, a CrCl3 monolayer grown on Graphene/6H-SiC (0001), which exhibits ferromagnetic ordering as unambiguously determined by element-specific X-ray magnetic dichroism [2]. Hysteretic behaviour of the field-dependent magnetization is sustained up to a temperature of 10 K, and angular dependent measurements evidence a clear in-plane easy axis, unlike all other van der Waals monolayer magnets reported to date. The origin of the easy-plane anisotropy is discussed in terms of a non-zero orbital moment and a trigonal distortion of the CrCl3 unit cell. Moreover, the analysis of the critical exponents of the temperature-dependent magnetization show a scaling behaviour that is characteristic of a 2D-XY system. These observations suggest the first realization of a finite-size Berezinskii-Kosterlitz-Thouless (BKT) phase transition in a quasi-freestanding monolayer magnet with a XY universality class; accessible through the bottom-up growth of a van der Waals layer with an in-plane hexagonal crystal symmetry and negligible substrate interaction.

Figure 1. (a) Schematic crystal structure of CrCl3/Graphene/6H-SiC layers in top view and cross-section configurations. (b) Atom resolved image of the CrCl3 lattice featuring a moiré pattern, which corresponds to a 23.8° rotation between the hexagonal unit cell of CrCl3 and graphene.(c) XMCD hysteresis loops taken in grazing (in-plane) and normal (out-of-plane) incidence, evidencing a weak anisotropy favouring an in-plane easy axis. (d) Modified Arrott-Plots for the temperature-and field dependent XMCD data. A consistent set of critical exponents is inferred (β=0.235, γ= 2.2), matching with the predictions of the 2DXY model.

[1] K. S. Burch, D. Mandrus, J. G. Park, Nature. 563, 47–52 (2018)
[2] A. Bedoya-Pinto et al., arXiV (2020)

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New Developments on Chromium Trihalides 2D Ferromagnets

David Soriano

The discovery of 2D ferromagnets in 2017 has opened new ways to explore novel physical phenomena at the nanoscale. In the first part of my talk, I will briefly discuss the recent advances in chromium trihalides, from fundamentals to applications.[1] In the second part, I will focus on our recent work regarding the role of Coulomb interactions in the intralayer exchange, the electrical tunability of interlayer magnetism in bilayer CrI3,[2] and the exchange proximity effects in van der Waals heterostructures containing chromium trihalides.[3,4] [1] Magnetic Two-Dimensional Chromium Trihalides: A Theoretical Perspective. D. Soriano, M. I. Katsnelson, and J. Fernández-Rossier. Submitted to Nano Letters.

[2] Magnetic polaron and antiferromagnetic-ferromagnetic transition in doped bilayer CrI3. D. Soriano, and M. I. Katsnelson. Phys. Rev. B 101, 041402(R) (2020)

[3] Van der Waals Spin Valves. C. Cardoso, N. A. García-Martínez, and J. Fernández-Rossier. Phys. Rev. Lett. 121, 067701 (2018)

[4] Exchange-bias controlled correlations in magnetically encapsulated twisted van der Waals dichalcogenides. D. Soriano, and J. L. Lado. arXiv:2006.09953

Program - Elastic Tuning and Response of Electronic Order





Monday, December 9th

Morning Session 

08:50 – 09:20 Registration
09:20 – 09:30 Opening Remarks
09:30 – 10:20 Ian FISHER, Stanford University
Feeling the strain: tuning the critical temperature of electronic nematic phases
10:30 – 10:50 Coffee Break
10:50 – 11:20 Anna BÖHMER, KIT
Tuning magnetism in iron-based superconductors
11:30 – 12:00 Bernd BÜCHNER, IFW
Strain dependent transport and nematicity in Fe based superconductors
12:00 – 14:30 Lunch Break

Afternoon Session

14:40 – 15:10 Elena GATI, IOWA State University
Effect of hydrostatic pressure and uniaxial stress on the competing phases in iron-based superconductors
15:20 – 15:50 Suguru HOSOI, Osaka University
Elastoresistance measurements in nematic superconductors
16:00 – 16:30 Collin BROHOLM, Johns Hopkins University
Magneto-elasticity in Fragile Magnets
18:00 – 19:30 Dinner

Tuesday, December 10th

Morning Session

09:00 – 09:50 Steven Allan KIVELSON, Stanford University
Nematicity, strain, and disorder: Universal features from statistical mechanics
10:00 – 10:30 Heejae KIM, Max Planck Institute for Polymer Research
Nonlinear spectroscopic study of electron-phonon coupling
10:30 – 10:50 Coffee Break & Poster Session
10:50 – 11:20 Rafael FERNANDES, University of Minnesota
Contrasting nematicity in rigid lattices and moiré superlattices
11:30 – 12:00 Kristin KLIEMT, University Frankfurt
Advanced methods for single crystal growth of Eu- and Yb-based intermetallic systems
12:00 – 14:30 Lunch Break & Poster Session

Afternoon Session

14:30 – 15:00 Stephen ROWLEY, Cambridge
Strong electron pairing in ferroelectric superconductors
15:10 – 15:40 Philipp GEGENWART, University of Augsburg
Thermal expansion signatures of the quadrupolar Kondo effect
15:50 – 16:20 Marcel SCHRODIN, KIT
Nanoscale sensing with single spins in diamond
16:20 – 17:30 Poster Session
18:00 – 19:30 Dinner

Wednesday, December 11th

Morning Session

09:00 – 09:50 Michael LANG, University of Frankfurt
Molecular metals – test ground for correlated electrons in a compressible lattice
10:00 – 10:30 Clifford HICKS, MPG
Superconductors and magnets under uniaxial stress
10:30 – 10:50 Coffee Break 
10:50 – 11:20 Helen GOMONAY, JGU
Elastic manipulation of antiferromagnetic domain structure
11:30 – 12:00 Kristin WILLA, KIT
Evidence for nematic superconductivity in the superconducting doped topological insulators NbxBi2Se3 and SrxBi2Se3
12:00 – 14:30 Lunch 

Afternoon Session 

14:30 – 15:00 Stuart BROWN, UCLA
Unconventional superconductivity in Sr2RuO4, probed under stressed conditions
15:10 – 15:40 Taner YILDIRIM, NIST
Pressure and Strain Control of Crystal Symmetry, Fermi Surface Reconstruction and Superconductivity in Weyl semimetal MoTe2
15:50 – 16:00 Closing Remarks


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20.12.2017 – Job offer: PhD Position in Spintronics in the Institute of Physics at the Johannes Gutenberg-Universität Mainz


PhD Position in Spintronics

Johannes Gutenberg-Universität Mainz, Germany


We are pleased to announce the opening of two PhD positions in theoretical condensed matter in the Institute of Physics at the Johannes Gutenberg-Universität Mainz to work with the spintronics theory groups INSPIRE (Jairo Sinova) and TWIST (Karin Everschor- Sitte) on topics such as antiferromagnetic spintronics, skyrmions, and topological matter. The physics institute and the Spin Phenomena Interdisciplinary Center (SPICE) provides a stimulating environment due to an active workshop program and a broad range of research activities.

The prospective group member must hold a MSc or equivalent diploma. A background in theoretical techniques in condensed matter physics is required. Candidates interested and/or experienced in spintronics, magnetization dynamics, the physics of antiferromagnetics or skyrmions, and micromagnetic modelling are highly suited for this opportunity. Programming experience is desired.

Further information can be found on the websites: or

Johannes Gutenberg-Universität Mainz is an equal opportunity, affirmative actions employer in compliance with German disability laws. Women and persons with disabilities are encouraged to apply.

Review of applications begins immediately and will continue until the position is filled. Interested applicants should send a curriculum vitae, a list of publications, and at least two letters of recommendation to When sending applications please use the subject line “Spintronics PhD position application”.



Prof. Jairo Sinova
Head of the group INSPIRE
Director of SPICE

Dr. Karin Everschor-Sitte
Head of Emmy Noether Research Group TWIST
Scientific Coordinator of SPICE

Johannes Gutenberg-Universität Mainz FB 08 – Institut für Physik Staudingerweg 7
55128 Mainz

04.07.2016 – SPICE Team and INSPIRE Group Workshop in Sörgenloch


On July 4th and 5th the SPICE team and INSPIRE group had an internal group workshop in the picturesque village of Sörgenloch close to Mainz. In the nice atmosphere of Schloss Sörgenloch the SPICE team and INSPIRE group focused on team building processes and internal working strategies. The group also used the occasion to welcome Ulrike Ritzmann, as well as Bertrand Dupé and Marie Böttcher, who will join the group in October 2016. After a very successful first day, the group enjoyed the food and a variety of local wines served on the Schloss Sörgenloch terrace in the evening. On the second day of the workshop the group worked on presentation techniques and communication skills under the guidance of two coaches from an improvisational theater. We thank the participants for two beautiful and very successful days in Sörgenloch..