Back Group
Welcome to the research pages of the Chair of Experimental Physics of Functional Spin-Systems, led by Prof. Dr. Christian H. Back. Our research focuses on fundamental magnetic properties and magnetisation dynamics in hybrid materials comprising ultrathin magnetic layers. We combine high-resolution magnetic microscopy techniques with microwave excitation and detection to explore magnetisation dynamics, the propagation of spin waves, and the efficiency of charge-to-spin current conversion in a wide range of material systems – including magnetic 2D materials and topological materials. Our work is embedded in both the Center for Quantum Engineering (ZQE) and the Munich Center for Quantum Science and Technology (MCQST).
Research
Our research covers a broad range of topics in modern magnetism and spintronics. A central theme is the study of spin waves and magnonics: we use time-resolved magneto-optical Kerr microscopy to image spin-wave propagation – for instance in ring-shaped magnonic waveguides1 – and develop novel readout schemes based on nitrogen-vacancy centres in diamond2. We furthermore investigate complex spin structures in topological materials, studying magnetic skyrmions in B20 silicides and Cu2OSeO3 as model systems for topologically non-trivial spin textures3, as well as hybrid structures that combine three-dimensional topological insulators with ultrathin magnetic layers for efficient spin-to-charge conversion4.
In the field of spinorbitronics, we explore spin-orbit torque driven switching on sub-nanosecond timescales5. A highlight of our recent work, published in Nature in 2024, was the demonstration that an in-plane charge current in Pt can modify the magnetic energy landscape of an adjacent Fe layer – a direct signature of magnetism control by the flow of angular momentum6. Magnetisation dynamics on picosecond timescales, including subtle effects like emerging anisotropic Gilbert damping and interfacial tuning of damping parameters7, remain at the core of our experimental programme.
1F. Vilsmeier et al., Spin wave propagation in a ring-shaped magnonic waveguide, Appl. Phys. Lett. 127, 162405 (2025). DOI: 10.1063/5.0287832
2C. Lüthi et al., Long-range spin wave imaging with nitrogen vacancy centres and time resolved magneto-optical measurements, Rev. Sci. Instrum. 96, 033703 (2025). DOI: 10.1063/5.0243762
3S. Mehboodi et al., Observation of distorted tilted conical phase at the surface of a bulk chiral magnet, Sci. Technol. Adv. Mater. 26(1), 2532366 (2025). DOI: 10.1080/14686996.2025.2532366
4A. Aqeel et al., Spin Hall magnetoresistance and spin Seebeck effect in Pt|CoCr₂O₄ heterostructures, Sci. Technol. Adv. Mater. 26(1), 2457320 (2025). DOI: 10.1080/14686996.2025.2457320
5Y. Wang et al., Time-resolved detection of spin-orbit torque switching of magnetisation and exchange bias, Nat. Electron. 5, 840–848 (2022). DOI: 10.1038/s41928-022-00870-3
6L. Chen et al., Signatures of magnetism control by flow of angular momentum, Nature 633, 548–553 (2024). DOI: 10.1038/s41586-024-07914-y
7L. Chen et al., Interfacial tuning of anisotropic Gilbert damping, Phys. Rev. Lett. 130, 046704 (2023). DOI: 10.1103/PhysRevLett.130.046704
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description => protected'<p>Welcome to the research pages of the Chair of Experimental Physics of Fun
ctional Spin-Systems, led by Prof. Dr. Christian H. Back. Our research focus
es on fundamental magnetic properties and magnetisation dynamics in hybrid m
aterials comprising ultrathin magnetic layers. We combine high-resolution ma
gnetic microscopy techniques with microwave excitation and detection to expl
ore magnetisation dynamics, the propagation of spin waves, and the efficienc
bedded in both the <i>Center for Quantum Engineering (ZQE)</i> and the <i>Mu
nich Center for Quantum Science and Technology (MCQST)</i>.</p>
<h2><span><
strong>Research</strong></span></h2>
<p>Our research covers a broad range o
f topics in modern magnetism and spintronics. A central theme is the study o
f spin waves and magnonics: we use time-resolved magneto-optical Kerr micros
copy to image spin-wave propagation – for instance in ring-shaped magnonic
waveguides<a class="sdfootnoteanc" href="t3://page?uid=current#sdfootnote1s
ym"><sup>1</sup></a> – and develop novel readout schemes based on nitrogen
-vacancy centres in diamond<a class="sdfootnoteanc" href="t3://page?uid=curr
ent#sdfootnote2sym"><sup>2</sup></a>. We furthermore investigate complex spi
n structures in topological materials, studying magnetic skyrmions in B20 si
licides and Cu<sub>2</sub>OSeO<sub>3</sub> as model systems for topologicall
y non-trivial spin textures<a class="sdfootnoteanc" href="t3://page?uid=curr
ent#sdfootnote3sym"><sup>3</sup></a>, as well as hybrid structures that comb
ine three-dimensional topological insulators with ultrathin magnetic layers
for efficient spin-to-charge conversion<a class="sdfootnoteanc" href="t3://p
age?uid=current#sdfootnote4sym"><sup>4</sup></a>.</p>
<p>In the field of sp
inorbitronics, we explore spin-orbit torque driven switching on sub-nanoseco
nd timescales<a class="s...' (4633 chars)
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Fundamental magnetic properties and magnetization dynamics in hybrid materials
Pfleiderer Group
A defining contribution of our group was the first experimental observation of magnetic skyrmions in a bulk crystal: the discovery of spontaneous skyrmion lattice formation in the chiral magnet MnSi [1], which launched the field of skyrmionics. We continue to shape this field as coordinators of the DFG Priority Programme SPP 2137 “Skyrmionics”, with current work spanning the optical creation and annihilation of skyrmion patches [2] and the discovery of topological magnon band structures emerging as Landau levels within skyrmion lattices [3].
A second major thrust concerns the topology of electronic band structures in quantum materials. We have demonstrated symmetry-enforced topological nodal planes at the Fermi surface of MnSi [4] and mapped networks of nodal planes, multifold degeneracies, and Weyl points in the chiral topological semimetal CoSi [5, 6]. In CoSi we further discovered a new generic phenomenon: quantum oscillations of the quasiparticle lifetime persisting to unusually high temperatures above 50 K [7] – revealing a fundamentally new mechanism for quantum oscillations in metals.
1We also investigate quantum phase transitions and non-Fermi liquid behaviour. Our early work revealed partial order in the non-Fermi-liquid phase of MnSi under pressure [8], a landmark result in quantum criticality. We have since discovered the emergence of mesoscale quantum phase transitions in a ferromagnet [9] and study materials hosting unconventional superconductivity and competing forms of electronic order. Advanced spectroscopic methods – including resonant elastic X-ray scattering (REXS) [10] and neutron scattering – provide complementary access to magnetic and electronic order across all of these research directions.
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1], which launched the field of skyrmionics. We continue to shape this field
as coordinators of the DFG Priority Programme SPP 2137 “Skyrmionics”, w
ith current work spanning the optical creation and annihilation of skyrmion
patches [2] and the discovery of topological magnon band structures emerging
as Landau levels within skyrmion lattices [3].<br />A second major thrust c
oncerns the topology of electronic band structures in quantum materials. We
have demonstrated symmetry-enforced topological nodal planes at the Fermi su
rface of MnSi [4] and mapped networks of nodal planes, multifold degeneracie
s, and Weyl points in the chiral topological semimetal CoSi [5, 6]. In CoSi
we further discovered a new generic phenomenon: quantum oscillations of the
quasiparticle lifetime persisting to unusually high temperatures above 50 K
[7] – revealing a fundamentally new mechanism for quantum oscillations in
metals.<br />1We also investigate quantum phase transitions and non-Fermi li
quid behaviour. Our early work revealed partial order in the non-Fermi-liqui
d phase of MnSi under pressure [8], a landmark result in quantum criticality
. We have since discovered the emergence of mesoscale quantum phase transiti
ons in a ferromagnet [9] and study materials hosting unconventional supercon
ductivity and competing forms of electronic order. Advanced spectroscopic me
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Fundamental magnetic properties and magnetization dynamics in hybrid materials
Weig Group
The research of our group is focused on the detailed understanding of fundamental magnetic properties and magnetization dynamics in hybrid materials comprising of ultrathin magnetic layers such as magnetic 2D materials in combination with topological materials or with materials inducing strong interfacial spin-orbit interaction and ideally in all 2D stacks. We tailor novel hybrid magnetic structures and investigate their static and dynamic magnetic properties. Among the subjects covered in our research are the dynamics in confined magnetic systems, magnonics, spin orbitronics, hybrid topological materials, high resolution magnetic microscopy as well as magnetic phase transitions in low dimensional systems. In our group we use several techniques to examine magnetization dynamics, the propagation of spinwaves and the efficiency of charge to spin current conversion. At the heart of our research projects are various time and spatially resolved high resolution magnetic microscopy techniques in combination with microwave excitation and detection.
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Fundamental magnetic properties and magnetization dynamics in hybrid materials