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Dr.  Christoph Sürgers

Dr. Christoph Sürgers

Akad. Direktor
AG Wernsdorfer
RaumCS
christoph suergersGtd4∂kit edu

www.phi.kit.edu

Electronic transport in metallic thin films and nanostructures

Current projects focus on the anomalous Hall effect in antiferromagnetic films and single crystals, on spininjection and -manipulation in CMOS-compatible heterostructures, and on the conductance of magnetostrictive nanocontacts.

Anomalous Hall effect in antiferromagnets

Magnetic structure of Mn5Si3 below 60 K where the arrangement is strongly noncollinear. In contrast to what one might expect, certain antiferromagnetic metals with a noncollinear and nonplanar arrangement of magnetic moments exhibit a large anomalous Hall effect despite a tiny magnetization. The anomalous Hall effect arises from an intrinsic property of the electronic band structure called Berry curvature which is nonzero due to the breaking of the total symmetry.

Recent publication:
Switching of a large anomalous Hall effect between metamagnetic phases of a non-collinear antiferromagnet.Sürgers, C.; Wolf, T.; Adelmann, P.; Kittler, W.; Fischer, G.; Löhneysen, H. v., Scientific reports 7 (2017), Art.Nr.: 42982.

 

Spininjection and spinmanipulation in CMOS-compatible heterostructures

APL 105, 222408 (2014)
In this cooperative project between the Physikalisches Institut (PHI) and the Institute of Semiconductortechnology (IHT) at the University of Stuttgart we aim to demonstrate spininjection, -detection and –manipulation in CMOS-compatible devices. Mn5Si3C und Mn5Ge3C compounds with Curie temperatures of 350 K and 450 K, respectively, serve as ferromagnetic electrodes for spininjection into Ge-  and Si-based semiconductor heterostructures which are characterized by measurements of electronic and thermal transport measurements. The project is supported by the Deutsche Forschungsgemeinschaft (DFG).

Conductance of magnetoresistive nanocontacts

Nanocontacts with contact areas as small as the diameter of one atom can be obtained by bending a freely suspending thin-film microstructure or a thin metallic wire on a flexible substrate. The bending can be fine tuned by a piezoelectric-driven piston. We use this technique to study magnetostrictive transition-metal nanocontacts to explore ways to remotely control their conductance by an applied magnetic field.

Recent publication:
Magnetostrictive Fe_73Ga_27 nanocontacts for low-field conductance switching. Kannan, U. M.; Kuntz, S.; Berg, O.; Kittler, W.; Basumatary, H.; Chelvane, J. A.; Sürgers, C.; Jammalamadaka, S. N. Applied Physics Letters 108 (2016), Art. Nr. 242408.

Experimental methods

  • Preparation of thin films and multilayers by electron-beam evaporation and magnetron sputtering
  • Mechanically controlled break-junctions
  • In-situ surface characterization, x-ray diffraction, magneto-optical Kerr effect
  • Electronic transport measurements (resistivity, Hall effect, electric-field effect) at low temperatures and in magnetic fields

Christoph Sürgers

Researcher ID-2873-2013

Publications of the last five years


2018
Creation of equal-spin triplet superconductivity at the Al/EuS interface.
Diesch, S.; Machon, P.; Wolz, M.; Sürgers, C.; Beckmann, D.; Belzig, W.; Scheer, E.
2018. Nature Communications, 9 (1), Article no 5248. doi:10.1038/s41467-018-07597-w
Local Joule Heating Mimicking Electroresistance-Like Behavior in Antiperovskite Mn3GaC.
Deng, S.; Fischer, G.; Srichandan, S.; Wang, L.; Wang, C.; Sürgers, C.
2018. Advanced electronic materials, 4 (9), Art.-Nr.:1800028/1–6. doi:10.1002/aelm.201800028
Phase separation and zero thermal expansion in antiperovskite Mn₃Zn0.77Mn0.19N0.94 : An in situ neutron diffraction investigation.
Deng, S.; Sun, Y.; Wu, H.; Shi, Z.; Wang, L.; Yan, J.; Shi, K.; Hu, P.; Diao, X.; Huang, Q.; Sürgers, C.; Wang, C.
2018. Scripta materialia, 146, 18–21. doi:10.1016/j.scriptamat.2017.10.031
2017
Signature of f-electron conductance in α-Cer single-atom contacts.
Kuntz, S.; Berg, O.; Sürgers, C.; Löhneysen, H. von.
2017. Physical review / B, 96, 085120. doi:10.1103/PhysRevB.96.085120
Quasi-metallic behavior of ZnO grown by atomic layer deposition : The role of hydrogen.
Beh, H.; Hiller, D.; Bruns, M.; Welle, A.; Becker, H.-W.; Berghoff, B.; Sürgers, C.; Merz, R.; Zacharias, M.
2017. Journal of applied physics, 122 (2), Art. Nr. 025306. doi:10.1063/1.4994175
Thermoelectric effects in superconductor-ferromagnet tunnel junctions on europium sulfide.
Kolenda, S.; Sürgers, C.; Fischer, G.; Beckmann, D.
2017. Physical review / B, 95 (22), Art. Nr. 224505. doi:10.1103/PhysRevB.95.224505
15 cm-1 to 12 000 cm-1 spectral coverage without changing optics: Diamond beam splitter adaptation of an FTIR spectrometer.
Strelnikov, D.; Kern, B.; Sürgers, C.; Kappes, M. M.
2017. Review of scientific instruments, 88 (2), 023118. doi:10.1063/1.4976744
Switching of a large anomalous Hall effect between metamagnetic phases of a non-collinear antiferromagnet.
Sürgers, C.; Wolf, T.; Adelmann, P.; Kittler, W.; Fischer, G.; Löhneysen, H. von.
2017. Scientific reports, 7, Art.Nr.: 42982. doi:10.1038/srep42982
2016
Two-band superconductivity of bulk and surface states in Ag thin films on Nb.
Tomanic, T.; Schackert, M.; Wulfhekel, W.; Sürgers, C.; Löhneysen, H. v.
2016. Physical review / B, 94 (22), Art.Nr.: 220503. doi:10.1103/PhysRevB.94.220503
Controlled electromigration and oxidation of free-standing copper wires.
Hauser, J. S.; Schwichtenberg, J.; Marz, M.; Sürgers, C.; Seiler, A.; Gerhards, U.; Messerschmidt, F.; Hensel, A.; Dittmeyer, R.; Löhneysen, H. v.; Hoffmann-Vogel, R.
2016. Applied physics / A, 122, 1068. doi:10.1007/s00339-016-0600-z
Magnetostrictive Fe_73Ga_27 nanocontacts for low-field conductance switching.
Kannan, U. M.; Kuntz, S.; Berg, O.; Kittler, W.; Basumatary, H.; Chelvane, J. A.; Sürgers, C.; Jammalamadaka, S. N.
2016. Applied physics letters, 108, Art. Nr. 242408. doi:10.1063/1.4953873
Second-Harmonic Generation from ZnO/Al2O3 Nanolaminate Optical Metamaterials Grown by Atomic-Layer Deposition.
Wickberg, A.; Kieninger, C.; Sürgers, C.; Schlabach, S.; Mu, X.; Koos, C.; Wegener, M.
2016. Advanced optical materials, 4 (8), 1203–1208. doi:10.1002/adom.201600200
Anomalous Hall effect in the noncollinear antiferromagnet Mn5Si3.
Sürgers, C.; Kittler, W.; Wolf, T.; Löhneysen, H. von.
2016. AIP Advances, 6 (5), Art. Nr.: 055604. doi:10.1063/1.4943759
2015
Remote control of magnetostriction-based nanocontacts at room temperature.
Jammalamadaka, S. N.; Kuntz, S.; Berg, O.; Kittler, W.; Kannan, U. M.; Chelvane, J. A.; Sürgers, C.
2015. Scientific Reports, 5, 13621. doi:10.1038/srep13621
2014
Large topological Hall effect in the non-collinear phase of an antiferromagnet.
Sürgers, C.; Fischer, G.; Winkel, P.; Löhneysen, H. von.
2014. Nature Communications, 5, Art.Nr. 3400. doi:10.1038/ncomms4400
Fabrication and magnetic characterization of nanometer-sized ellipses of the ferromagnetic insulator EuS.
Wolf, M. J.; Sürgers, C.; Fischer, G.; Scherer, T.; Beckmann, D.
2014. Journal of magnetism and magnetic materials, 368 (November), 49–53. doi:10.1016/j.jmmm.2014.04.067
Magnetotransport in ferromagnetic Mn₅Ge₃, Mn₅Ge₃C₀̣₈ and Mn₅Si₃C₀̣₈ thin films.
Sürgers, C.; Fischer, G.; Winkel, P.; Löhneysen, H. von.
2014. Physical review / B, 90 (10), Art.Nr. 104421. doi:10.1103/PhysRevB.90.104421
Spin-polarized quasiparticle transport in exchange-split superconducting aluminum on europium sulfide.
Wolf, M. J.; Sürgers, C.; Fischer, G.; Beckmann, D.
2014. Physical review / B, 90 (14), Art.Nr. 144509. doi:10.1103/PhysRevB.90.144509
Hanle-effect measurements of spin injection from Mn5Ge3C0.8/Al2O3-contacts into degenerately doped Ge channels on Si.
Fischer, I. A.; Chang, L.-T.; Sürgers, C.; Rolseth, E.; Reiter, S.; Stefanov, S.; Chiussi, S.; Tang, J.; Wang, K. L.; Schulze, J.
2014. Applied Physics Letters, 105 (22), Article Nr. 222408. doi:10.1063/1.4903233
Temperature-dependent scanning tunneling spectroscopy on the Si(557)-Au surface.
Sauter, M.; Hoffmann, R.; Sürgers, C.; Löhneysen, H. von.
2014. Physical review / B, 89 (7), Art.Nr. 075406. doi:10.1103/PhysRevB.89.075406