Head: Dr. L. Veyrat
We investigate emergent phenomena of quantum matter such as low-dimensional magnetism, unconventional superconductivity, or topological states. Transport of charge and entropy, in either bulk materials or nanoscale devices, provides important information about unconventional quasiparticles. Their spectral and scattering properties are probed in bulk samples, whereas the quasi-particle phase, their quantum interference, and decoherence are accessed in quantum transport experiments in nanoelectronic devices. At even smaller scales, we map out real-space variations of the electronic local density of states (LDOS) and of the magnetic structure with low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and magnetic force microscopy (MFM), respectively.
We investigate quantum magnetism primarily by transport measurements. Low-dimensional quantum magnets, such as spin chains, ladders, planes, often possess a highly unusual mode of heat transport which is carried by the elementary excitations of those systems. We use this quantum-magnetic heat transport in order to probe the low-energy physics of these excitations, viz. the nature of their thermal generation and their scattering.
We use transport measurements for investigating the normal state of unconventional superconductors. This includes the exploration of electronic phase diagrams of novel superconducting materials, as well as dedicated Hall-, Seebeck-, and Nernst effect measurements which aim at revealing peculiar electronic properties of selected compounds. As a very powerful method for addressing the superconducting state, we apply high-resolution STM/STS, because superconductivity is probed on a local scale. From registering spatial variations of the LDOS, e.g. caused by a magnetic field or impurities, we extract information on microscopic parameters, the momentum space electronic structure, and even the pairing symmetry.
Carbon-based materials and molecular nanostructures, such as graphene and molecular magnets possess a proven application potential. We use STM/STS for exploring the real-space electronic structure of pertinent materials and systems.
Topology is a powerful paradigm in quantum condensed-matter physics, and the importance of geometric phases in band theory has recently gained new prominence with the discovery of Z2 topological insulators (TIs). We study the physics of their gapless states in nanostructures of 3D TIs, such as Bi2Se3, where surface-state transport results from topologically-protected electronic states (spin-chiral Dirac fermions). Such quasi-particles have unique properties (suppression of localization, weak scattering by disorder,...) which can be revealed by quantum transport studies of nanowires/ribbons (quantum interferences, proximity effect with superconducting or ferromagnetic contacts).
Our nanoscale chemistry group supported by the synthesis and crystal growth group successfully synthesized single crystalline nanomagnets embedded in carbon nanotubes (CNT). These hybrid nanosystems are characterized by a very high mechanical and chemical stability, high magnetic shape anisotropy and exceptionally narrow switching field distributions. We investigate magnetic properties including anisotropy and magnetization reversal of individual single domain nanomagnets. Furthermore we are developing nanomagnetometry concepts to bridge the gap between conventional cantilever force detection methods and ultrasensitive CNT oscillator approaches. Studies of the interplay of kinematics and magnetism of individual ferromagnetic nanowires include the investigation of rapidly repeated magnetization reversal that is induced by the flexural vibration of cantilevered nanowires.
Our development of monopole-type magnetic force microscopy (MFM) probes based on filled carbon nanotubes allows for straightforward high-resolution quantitative MFM measurements. In particular the bidirectional sensor type is simultaneously sensitive to magnetic field derivatives parallel and perpendicular to the sample’s surface.
Furthermore, we develop MFM and magnetometry sensors based on coupled mechanical oscillators. We combine the high sensitivity of a nanowire resonator with the easy detection capability of a state-of-the-art micron-sized cantilever by co-resonant coupling of the two mechanical resonators. The term “co-resonant” refers to the important case when the eigenfrequencies of the two mechanical beams are close to each other. Even though the nanowire’s mass and stiffness might be orders of magnitude smaller than those of the cantilever, very strong coupling phenomena can be expected in that case.
Group Leader: Dr. Vilmos Kocsis
Suppression of scattering in quantum confined 2D helical Dirac systems, J. Dufouleur et al, Physical Review B 97, 075401 (2018)
We study magnetic properties of individual nanoscaled magnets and develop multifunctional cantilever-type probes for magnetic force microscopy and cantilever magnetometry.
As an example, in one of our projects we explore a new approach for magnetostatic force detection employing a purely mechanical amplification effect when coupling a nanometer-sized and a micron-sized cantilever. We combine the high sensitivity of a nanowire resonator with the easy detection capability of a state-of-the-art micron-sized cantilever by co-resonant coupling of the two mechanical resonators, to produce a novel system with the best aspects of both nano and micro scale systems. The term “co-resonant” refers to the important case when the eigenfrequencies of the two mechanical beams are close to each other.
Group Leader: Dr. Thomas Mühl
Phone: +49 351 4659 496
Email: t(dot)muehl(at)ifw-dresden.de
2021
June: Our patent application about coupled cantilever-nanowire sensor systems has been granted (DE 10 2015 224 938).
June: Mykhailo Flaks successfully submitted his Master thesis titled “Magnetometry of weak electrical signals”, and defended it. He has secured the highest grade for his work.
March: Our patent application about force gradient microscopy has been granted (DE102011084434).
February: We welcome our new PhD student, Aniruddha Sathyadharma Prasad.
Expertise on device fabrication at the nanoscale
We mainly use a Kleindiek micromanipulator in a Zeiss 1540 XB CrossBeam (SEM-FIB combination) for nanofabrication and device preparation.
Examples of our work are present on the right.
How to prepare a nanosized musical instrument, e.g. a nano-ukulele?
Please find out here: https://www.youtube.com/watch?v=MA14yKVMbwY
N.H. Freitag, C.F. Reiche, V. Neu, P. Devi, U. Burkhardt, C. Felser, D. Wolf, A. Lubk, B. Büchner, T. Mühl
Simultaneous magnetic field and field gradient mapping of hexagonal MnNiGa by quantitative magnetic force microscopy
Communications Physics
6,
11/1-13
(2023) URL
N. Sato, K. Schultheiss, L. Körber, N. Puwenberg, T. Mühl, A. Awad, S. Arekapudi, O. Hellwig, J. Fassbender, H. Schultheiss
Domain Wall Based Spin-Hall Nano-Oscillators
Physical Review Letters
123,
057204/1-5
(2019) URL
N. Puwenberg, C.F. Reiche, R. Streubel, M. Khan, D. Mukherjee, I.V. Soldatov, M. Melzer, O.G. Schmidt, B. Büchner, T. Mühl
Magnetization reversal and local switching fields of ferromagnetic Co/Pd microtubes with radial magnetization
Physical Review B
99,
094438/1-8
(2019) URL
K. Lenz, R. Narkowicz, K. Wagner, C. Reiche, J. Körner, T. Schneider, A. Kákay, H. Schultheiss, U. Weissker, D. Wolf, D. Suter, B. Büchner, J. Fassbender, T. Mühl, J. Lindner
Magnetization Dynamics of an Individual Single‐Crystalline Fe‐Filled Carbon Nanotube
Small
15,
1904315/1-9
(2019) URL
J. Körner, C. Reiche, B. Büchner, T. Mühl
Theory and application of a novel co-resonant cantilever sensor
tm - Technisches Messen
85,
410-419
(2018) URL
S. Philippi, H. Schlörb, D. Mukherjee, B. Büchner, T. Mühl
Quasi-periodic magnetization reversal of ferromagnetic nanoparticles induced by torsional oscillations in static magnetic fields
Nanotechnology
29,
405503/2-11
(2018) URL
J. Körner, C.F. Reiche, R. Ghunaim, R. Fuge, S. Hampel, B. Büchner, T. Mühl
Magnetic properties of individual Co2FeGa Heusler nanoparticles studied at room temperature by a highly sensitive co-resonant cantilever sensor
Scientific Reports
7,
8881/1-12
(2017) URL
J. Koerner, C.F. Reiche, T. Gemming, B. Büchner, G. Gerlach, T. Muehl
Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor
Beilstein Journal of Nanotechnology
7,
1033-1043
(2016) URL
F. Klein, U. Treske, A. Koitzsch, D.R. Cavicchia, C. Thoenissen, R Froemter, T. Roch, T. Muehl
Nanoscale scanning electron microscopy based graphitization in tetrahedral amorphous carbon thin films
Carbon
107,
536-541
(2016) URL
J. Koerner, C.F. Reiche, B. Büchner, T. Muehl, G. Gerlach
Employing electro-mechanical analogies for co-resonantly coupled cantilever sensors
Journal of Sensors and Sensor Systems
5,
245-259
(2016) URL
R. Streubel, F. Kronast, C.F. Reiche, T. Muehl, A.U.B. Wolter, O.G. Schmidt, D. Makarov
Vortex circulation and polarity patterns in closely packed cap arrays
Applied Physics Letters
108,
042407/1-4
(2016) URL
T. Schwarz, R. Woelbing, C.F. Reiche, B. Mueller, M.J. Martínez-Perez, T. Muehl, B. Büchner, R. Kleiner, D. Koelle
Low-Noise YBa2Cu3O7 Nano-SQUIDs for Performing Magnetization-Reversal Measurements on Magnetic Nanoparticles
Physical Review Applied
3,
044011/1-10
(2015) URL
C.F. Reiche, J. Koerner, B. Büchner, T. Muehl
Introduction of a co-resonant detection concept for mechanical oscillation-based sensors
Nanotechnology
26,
335501/1-9
(2015) URL
C.F. Reiche, S. Vock, V. Neu, L. Schultz, B. Büchner, T. Muehl
Bidirectional quantitative force gradient microscopy
New Journal of Physics
17,
013014/1-10
(2015) URL
T. Roch, F. Klein, K. Guenther, A. Roch, T. Muehl, A. Lasagni
Laser interference induced nano-crystallized surface swellings of amorphous carbon for advanced micro tribology
Materials Research Express
1,
035042/1-14
(2014) URL
P. Philipp, L. Bischoff, U. Treske, B. Schmidt, J. Fiedler, R. Huebner, F. Klein, A. Koitzsch, T. Muehl
The origin of conductivity in ion-irradiated diamond-like carbon - Phase transformation and atomic ordering
Carbon
80,
677-690
(2014) URL
T. Muehl, J. Koerner, S. Philippi, C.F. Reiche, A. Leonhardt, B. Büchner
Magnetic force microscopy sensors providing in-plane and perpendicular sensitivity
Applied Physics Letters
101,
112401/1-5
(2012) URL
M. Loeffler, U. Weissker, T. Muehl, T. Gemming, B. Büchner
Robust determination of Young's modulus of individual carbon nanotubes by quasi-static interaction with Lorentz forces
Ultramicroscopy
111,
155-158
(2011) URL
S. Philippi, U. Weissker, T. Muehl, A. Leonhardt, B. Büchner
Room temperature magnetometry of an individual iron filled carbon nanotube acting as nanocantilever
Journal of Applied Physics
110,
084319/1-5
(2011) URL
F. Wolny, Y. Obukhov, T. Muehl, U. Weissker, S. Philippi, A. Leonhardt, P. Banerjee, A. Reed, G. Xiang, R. Adur, I. Lee, A.J. Hauser, F.Y. Yang, D.V. Pelekhov, B. Büchner, P.C. Hammel
Quantitative magnetic force microscopy on permalloy dots using an iron filled carbon nanotube probe
Ultramicroscopy
111,
1360-1365
(2011) URL
M. Loeffler, U. Weissker, T. Muehl, T. Gemming, J. Eckert, B. Büchner
Current-induced mass transport in filled multiwalled carbon nanotubes
Advanced Materials
23,
541-544
(2011) URL
F. Wolny, U. Weissker, T. Muehl, M.U. Lutz, C. Mueller, A. Leonhardt, B. Büchner
Stable magnetization of iron filled carbon nanotube MFM probes in external magnetic fields
Journal of Physics: Conference Series
200,
112011/1-4
(2010) URL
F. Wolny, T. Muehl, U. Weissker, K. Lipert, J. Schumann, A. Leonhardt, B. Büchner
Iron filled carbon nanotubes as novel monopole-like sensors for quantitative magnetic force microscopy
Nanotechnology
21,
435501/1-5
(2010) URL
S. Vock, F. Wolny, T. Muehl, R. Kaltofen, L. Schultz, B. Büchner, C. Hassel, J. Lindner, V. Neu
Monopolelike probes for quantitative magnetic force microscopy: Calibration and application
Applied Physics Letters
97,
252505/1-3
(2010) URL
P. Banerjee, F. Wolny, D.V. Pelekhov, M.R. Herman, K.C. Fong, U. Weissker, T. Muehl, Y. Obukhov, A. Leonhardt, B. Büchner, P.C. Hammel
Magnetization reversal in an individual 25 nm iron-filled carbon nanotube
Applied Physics Letters
96,
252505/1-3
(2010) URL
K. Lipert, S. Bahr, F. Wolny, P. Atkinson, U. Weissker, T. Muehl, O.G. Schmidt, B. Büchner, R. Klingeler
An individual iron nanowire-filled carbon nanotube probed by micro-Hall magnetometry
Applied Physics Letters
97,
212503/1-3
(2010) URL
M.U. Lutz, U. Weissker, F. Wolny, C. Mueller, M. Loeffler, T. Muehl, A. Leonhardt, B. Büchner, R. Klingeler
Magnetic properties of a-Fe and Fe3C nanowires
Journal of Physics: Conference Series
200,
072062/1-4
(2010) URL
F. Wolny, T. Muehl, U. Weissker, A. Leonhardt, U. Wolff, D. Givord, B. Büchner
Magnetic force microscopy measurements in external magnetic fieldscomparison between coated probes and an iron filled carbon nanotube probe
Journal of Applied Physics
108,
013908/1-4
(2010) URL
U. Weissker, M. Loeffler, F. Wolny, M.U. Lutz, N. Scheerbaum, R. Klingeler, T. Gemming, T. Muehl, A. Leonhardt, B. Büchner
Perpendicular magnetization of long iron carbide nanowires inside carbon nanotubes due to magnetocrystalline anisotropy
Journal of Applied Physics
106,
054909/1-5
(2009) URL
S. Myhra, T. Muehl
Surface patterning of a-C DLC films: aqueous electrochemistry and thermal activation
Journal of Physics D-Applied Physics
42,
035309/1-8
(2009) URL
F. Wolny, U. Weissker, T. Muehl, A. Leonhardt, S. Menzel, A. Winkler, B. Büchner
Iron-filled carbon nanotubes as probes for magnetic force microscopy
Journal of Applied Physics
104,
064908/1-5
(2008) URL
T. Muehl, S. Myhra
Aqueous electro-oxidative probe-based patterning of diamond-like carbon films
Nanotechnology
18,
155304-155309
(2007) URL
T. Muehl, S. Myhra
Patterning of a-C DLC films: exploration of an aqueous electro-oxidative mechanism
Journal of Physics D-Applied Physics
40,
3468-3477
(2007) URL
R. Kozhuharova-Koseva, M. Hofmann, A. Leonhardt, I. Moench, T. Muehl, M. Ritschel, B. Büchner
Relation between growth parameters and morphology of vertically aligned Fe-filled carbon nanotubes
Fullerenes, Nanotubes and Carbon Nanostructures
15,
135-143
A. Winkler, T. Muehl, S. Menzel, R. Kozhuharova-Koseva, S. Hampel, A. Leonhardt, B. Buechner
Magnetic force microscopy sensors using iron-filled carbon nanotubes
Journal of Applied Physics
99,
104905/1-5
(2006) URL
S. Groudeva-Zotova, R. Kozhuharova, D. Elefant, T. Muehl, C.M. Schneider, I. Moench
Phase composition and magnetic characteristics of Fe-filled multi-walled carbon nanotubes
Journal of Magnetism and Magnetic Materials
306,
40-50
(2006) URL
R. Kozhuharova, M. Ritschel, I. Moench, T. Muehl, A. Leonhardt, A. Graff, C.M. Schneider
Selective growth of aligned Co-filled carbon nanotubes on silicon substrates
Fullerenes, Nanotubes and Carbon Nanostructures
13,
347-353
V. Sohatsky, S. Kolesnik, D. Makarov, A. Leonhardt, T. Muehl, I. Moench, M. Ritschel, R.K. Kozhuharova, J. Schumann, C.M. Schneider
ESR of Fe-filled multi-walled carbon nanotubes
Fullerenes, Nanotubes and Carbon Nanostructures
13,
401-410
R. Kozhuharova, M. Ritschel, D. Elefant, A. Graff, I. Moench, T. Muehl, C.M. Schneider, A. Leonhardt
(FexCo1-x)-alloy filled vertically aligned carbon nanotubes grown by thermal chemical vapor deposition
Journal of Magnetism and Magnetic Materials
290-291,
250-253
(2005) URL
T. Ruskov, S. Asenov, I. Spirov, C. Garcia, I. Moench, A. Graff, R. Kozhuharova, A. Leonhardt, T. Muehl, M. Ritschel, C.M. Schneider, S. Groudeva-Zotova
Moessbauer transmission and back scattered conversion electron study of Fe nanowires encapsulated in multiwalled carbon nanotubes
Journal of Applied Physics
96,
7514-7518
(2004) URL
C.M. Schneider, B. Zhao, R. Kozhuharova, S. Groudeva-Zotova, T. Muehl, M. Ritschel, I. Moench, H. Vinzelberg, D. Elefant, A. Graff, A. Leonhardt, J. Fink
Towards molecular spintronics: magnetotransport and magnetism in carbon nanotube-based systems
Diamond and Related Materials
13,
215-220
(2004) URL
T. Muehl
Scanning-tunneling-microscopy-based nanolithography of diamond-like carbon films
Applied Physics Letters
85,
5727-5729
(2004) URL
R. Kozhuharova, M. Ritschel, D. Elefant, A. Graff, A. Leonhardt, I. Moench, T. Muehl, S. Groudeva-Zotova, C.M. Schneider
Well-aligned Co-filled carbon nanotubes: preparation and magnetic properties
Applied Surface Science
238,
355-359
(2004) URL
A. Leonhardt, M. Ritschel, R. Kozhuharova, A. Graff, T. Muehl, R. Huhle, I. Moench, D. Elefant, C.M. Schneider
Synthesis and properties of filled carbon nanotubes
Diamond and Related Materials
12,
790-793
(2003) URL
R. Kozhuharova, M. Ritschel, D. Elefant, A. Graff, A. Leonhardt, I. Moench, T. Muehl, C.M. Schneider
Synthesis and characterization of aligned Fe-filled carbon nanotubes on silicon substrates
Journal of Materials Science-Materials in Electronics
14,
789-791
T. Muehl, D. Elefant, A. Graff, R. Kozhuharova, A. Leonhardt, I. Moench, M. Ritschel, P. Simon, S. Groudeva-Zotova, C.M. Schneider
Magnetic properties of aligned Fe-filled carbon nanotubes
Journal of Applied Physics
93,
7894-7896
(2003) URL
B. Zhao, I. Moench, H. Vinzelberg, T. Muehl, C.M. Schneider
Spin-coherent transport in ferromagnetically contacted carbon nanotubes
Applied Physics Letters
80,
3144-3146
(2002) URL
B. Zhao, I. Moench, T. Muehl, H. Vinzelberg, C.M. Schneider
Spin-dependent transport in multiwalled carbon nanotubes
Journal of Applied Physics
91,
7026-7028
(2002) URL
T. Muehl, J. Kretz, I. Moench, C.M. Schneider, H. Brueckl, G. Reiss
Parallel nanolithography in carbon layers with conductive imprint stamps
Applied Physics Letters
76,
786-788
(2000) URL
T. Muehl, H. Brueckl, D. Kraut, J. Kretz, I. Moench, G. Reiss
Nanolithography of metal films using scanning force microscopy patterned carbon masks
Journal of Vacuum Science & Technology B
16,
3879-3882
T. Muehl, H. Brueckl, G. Weise, G. Reiss
Nanometer-scale lithography in thin carbon layers using electric field assisted scanning force microscopy
Journal of Applied Physics
82,
5255-5258
(1997) URL
Verfahren und Vorrichtung zur Messung von Kraftgradienten bei der Kraftmikroskopie (DE102011084434). Patent granted on 15th March 2021.
Verfahren und Vorrichtung zur Ermittlung von Kraftfeldern, Kraftfeldgradienten, Materialeigenschaften oder Massen mit einem System aus gekoppelten, schwingungsfähigen, balkenartigen Komponenten (DE 10 2015 224 938). Patent granted on 15th June 2021.
With Koelle/Kleiner group (Solid state physics at Tübingen university)
Low-Noise YBa2Cu3O7 Nano-SQUIDs for Performing Magnetization-Reversal Measurements on Magnetic Nanoparticles, T. Schwarz, R. Woelbing, C.F. Reiche, B. Mueller, M.J. Martínez-Perez, T. Mühl, B. Büchner, R. Kleiner, D. Koelle, Physical Review Applied 3, 44011 (2015)
With Schultheiss group (Magnonics group, Helmholtz-Zentrum Dresden-Rossendorf)
Domain Wall Based Spin-Hall Nano-Oscillators, N. Sato, K. Schultheiss, L. Körber, N. Puwenberg, T. Mühl, A.A. Awad, S.S.P.K. Arekapudi, O. Hellwig, J. Fassbender, and H. Schultheiss, Phys. Rev. Lett. 123, 057204 (2019)
With Lindner group (Department of magnetism, Helmholtz-Zentrum Dresden-Rossendorf)
Magnetization Dynamics of an Individual Single-Crystalline Fe-Filled Carbon Nanotube, K. Lenz, R. Narkowicz, K. Wagner, C. F. Reiche, J. Körner, T. Schneider, A. Kákay, H. Schultheiss, U. Weissker, D. Wolf, D. Suter, B. Büchner, J. Fassbender, T. Mühl, and J. Lindner, SMALL 1904315 (2019)
Lectures at TU Dresden
Molecular Nanostructures (Lecturers: B. Büchner, J. Dufouleur, A. Popov, T. Mühl)
Magnetism on the Nanoscale (Lecturers: B. Büchner, S. Wurmehl, L. Corredor Bohorquez, J. Dufouleur, T. Mühl)
Lab courses
Scanning Probe Microscopy lab course at TU Dresden
In particular for students of the Nanobiophysics Master’s program we offer an annual lab course dedicated to high resolution microscopy. Organized and led by T. Mühl, supported by several supervisors at various microscopes (SEM, STM, TEM, AFM, MFM).
Group Leader:
Thomas Mühl
Industrial training as toolmaker, study of Physics at TU Dresden, PhD study at TU Dresden and IFW Dresden, research stay at National Taiwan University, postdoc position at University of Oxford, group leader at IFW Dresden.
PhD Students:
Norbert Puwenberg
Maneesha Sharma
Aniruddha Sathyadharma Prasad
Master Students:
Mykhailo Flaks
Former PhD students of our group:
Dr. Franziska Wolny (now at Fraunhofer Institute for Photonic Microsystems)
Dr. Uhland Weissker (now at SAWlab/IFW Dresden and in the TU Dresden knowledge and technology transfer team)
Dr. Stefan Philippi (now at Berliner Glas)
Dr. Frederik Engler (now at Evico, www.evico.de)
Prof. Dr.-Ing. Julia Körner (now at Leibniz University Hannover, www.geml.uni-hannover.de/de/koerner/)
Prof. Dr. Christopher F. Reiche (now Research Assistant Professor at University of Utah, www.utah.edu)
Former Diploma/Master students of our group:
Dr. Andreas Winkler (now head of the Acoustic Microsystems group at IFW Dresden)
Dr. Steve Kupke (founder of Unipolar, www.uni-polar.de)
Vladislav Khomenko (now at Infineon Technologies)
Clemens Gütter (now at NTT Data Business Solutions)
Heiko Hädrich (now providing services for website design)
Qifeng Pan (now at Stuttgart High-Performance Computing Center, www.hlrs.de)
Are you a Master student of natural sciences or engineering with interest in nano devices and magnetism? You are welcome to apply for a research project and/or Master thesis. Please get in touch with Thomas Mühl (Email: t(dot)muehl(at)ifw-dresden.de).
Helical quantum Hall phase in graphene on SrTiO3
L. Veyrat et al.
Group leader:
Louis Veyrat
PhD students:
Teresa Tschirner
Burak Özer
