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Experimental Physics of Functional Spin Systems

Prof. Christian Back

Research Field

The research of our group is focused on the detailed understanding of magnetization dynamics in hybrid materials comprising of ultrathin magnetic layers in combination with topological materials or with materials inducing strong interfacial spin-orbit interaction. 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.

Address/Contact

James-Franck-Str. 1
85748 Garching b. München
efs.office@ph.tum.de
+49 89 289 12401
Fax: +49 89 289 12414

Members of the Research Group

Professor

Office

Scientists

Students

Other Staff

Teaching

Course with Participations of Group Members

Titel und Modulzuordnung
ArtSWSDozent(en)Termine
Physik für Elektroingenieure
eLearning-Kurs
Zuordnung zu Modulen:
VO 4 Back, C. Do, 09:45–11:15, 1200
Mo, 09:45–11:15, 1200
Spin-Orbit-Felder und ihre Anwendungen
Zuordnung zu Modulen:
PS 2 Back, C.
Mitwirkende: CHEN, L.
Tutorübungen zu Physik für Elektroingenieure
eLearning-Kurs
Zuordnung zu Modulen:
UE 2 Sahliger, J.
Leitung/Koordination: Back, C.
Termine in Gruppen
Zentralübung zu Physik für Elektroingenieure
eLearning-Kurs
Zuordnung zu Modulen:
UE 2
Leitung/Koordination: Back, C.
Mi, 08:00–09:30, 1200
Aktuelle Themen zur Physik funktionaler Spinsysteme
Zuordnung zu Modulen:
SE 2 Back, C. Di, 14:00–16:00, PH 2024
Repetitorium zu Spin-Orbit-Felder und ihre Anwendungen
Zuordnung zu Modulen:
RE 2
Leitung/Koordination: Back, C.
Seminar zu aktuellen Themen zum Oberflächenmagnetismus
Zuordnung zu Modulen:
SE 2 Back, C. Mi, 14:00–16:00, PH 2024

Offers for Theses in the Group

Anomalous Hall torques in fully epitaxial heterostructures
The anomalous Hall effect (AHE), i.e., an additional Hall resistivity induced by the magnetization m in ferromagnetic materials, is a well-known effect. Although it was discovered more than a century ago, we deeply understood the underlying mechanism only recently. Experimentally, for most cases, this effect is discussed in term of generating transverse voltages or currents. In this Master thesis, we would like to demonstrate an unexplored property of the AHE: i.e., can the anomalous Hall effect generate a spin current and subsequently switch the magnetization of an ajacent ferromagnet? The prototypical sample is a fully epitaxial Fe/GaAs/GaMnAs heterostructure grown by molecular beam epitaxy, and the Hall bar device will be fabricated by electron-beam lithography.
suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Christian Back
Manipulation of interfacial spin-orbit interaction via the electronic density of states
Several years ago, we have shown that robust spin-orbit fields (SOFs) exist at the single crystalline Fe/GaAs interface. The SOFs originate from Byckov-Rashba and Dresselhaus spin-orbit interaction due to the reduced symmetry at the interface, and have the following properties: 1) The in-plane SOF is proportional to density of states (DOS) at Fermi level (EF). 2) The out-of-plane SOF is proportional to all the states below EF. It is well known that in the CoFe alloys the DOS at EF depends strongly on the relative concentrations. Therefore, it is expected that the interfacial SOFs can be manipulated by Co alloying. In this Master thesis, we will address the following points: 1) We will replace Fe by FexCo1-x, and carry out spin-orbit torque ferromagnetic resonance (SOT-FMR) measurements. 2) To prove that the SOFs can be modulated by Co alloying 3) If the above question is answered positively, we will try to switch the magnetization direction using a d.c. current.
suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Christian Back
Tracing in-plane magnetization switching dynamics by time-resolved magneto-optical Kerr microscopy
The demonstration of magnetization switching induced by spin-orbit torques in a ferromagnetic metal (FM)/heavy metal (HM) bilayer has attracted tremendous attention due to possible application in magnetic random access memories (MRAM). Typically, an in-plane current sent through the heavy metal layer (e.g. Pt) gives rise to a spin accumulation at the FM/HM interface due to the spin Hall effect. The spin accumulation acts on the ferromagnet (e.g. Co) via the spin transfer torque effect and leads to magnetization dynamics and, ideally, to switching. In this Master thesis, we will use time resolved magneto-optical Kerr microscopy (TRMOKE), which is a time and spatially resolved technique, to trace the switching dynamics of an in-plane magnetized ferromagnetic metal. The following points will be addressed: 1) The Co/Pt thin films will be patterned to micrometer-size devices by using a by mask-free laser writer or by electron-beam lithography. 2) Time and spatially resolved magnetization dynamics will be measured by TRMOKE. 3) Finally, the experimental data will be compared to theory.
suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Christian Back

Current and Finished Theses in the Group

Magnetization dynamics induced by spin orbit torques in heavy metal ferromagnet hybrid layers
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Christian Back
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