Growth and characterizations of hybrid heterostructures altermagnet/superconductor

Recently, a third type of magnetic materials, dubbed altermagnets, have been discovered in collinear antiferromagnets [1]. The specific symmetry of their spin structure gives rise to outstanding properties, gathering the advantages of ferromagnets (spin splitting - though highly anisotropic in momentum space-, finite anomalous magnetotransport and magnetooptical effects) and antiferromagnetic materials (vanishing magnetization by symmetry, ultrafast dynamics). The distinctive band structures of altermagnets makes it possible to expand core spin physics with altermagnets (giant or tunneling magnetoresistance effect for instance) and open up prospects for novel and interesting phenomena such as topological superconductivity. However, these theoretical predictions still require experimental demonstration. This is partly due to the scarcity of experimentally available materials (<5). The SPIXY team at CINaM has pioneered the epitaxial growth of one of them (Mn₅Si₃) barely one year after the first predictions of altermagnet [2-7] and is now developing the controlled growth of a second one (MnTe). In this context, the ANR-DFG HEXAS project tackles two main issues that are the experimental observation of (i) the tunnel magnetoresistance and spin transfer torque effects, (ii) spin polarized triplet-superconductivity in Mn-based altermagnets.

The work will be carried out within the SPIXY team at CINaM. Using molecular beam epitaxy (MBE), the candidate will have in charge the growth of dedicated heterostructures to experimentally demonstrate such effects. She/he will conduct their advanced structural, chemical and magnetic characterizations. Synchrotron experiments (such as ARPES, XMCD…) may be considered. To optimize material properties and heterostructure design, the candidate will work closely with other teams in our long-term consortium (France, Germany, Czechia - see e.g. Refs 2-6) in which transport measurements and theoretical modeling will be carried out. This complete picture will allow to unveil the underlying physical mechanisms of altermagnetic-based spintronics.

References: (our publications are indicated in bold characters)

[1] L. Smejkal et al., Phys. Rev. X 12, 040501 (2022)                          

[2] I. Kounta et al., Phys. Rev. Materials (2023)

[3] H. Reichlova et al., Nature Communications 15, 4961 (2024    

[4] M. Leiviskä et al., Phys. Rev. B 109, 224430 (2024)

[5] J. Rial et al., Phys. Rev. B 110, L220411 (2024)                                       

[6] A. Badura et al., arXiv:2403.12929 (2024)

[7] L. Han et al., arXiv:2403.13427 (2024)

The CINaM lab is a research mixed unit between CNRS and the Aix-Marseille University. With more than 140 staff members, including CNRS researchers and researcher-lecturers from the Aix-Marseille University, CINaM conducts research in nanosciences both from the physical and chemical approaches. CINaM is one of the most well-known centers in France in the field of elaboration and characterizations of Si/Ge nanostructures. CINaM is equipped with numerous MBE and CVD growth systems devoted to the synthesis of Si/Ge nanostructures, tools for surface analysis, such as low-temperature STM, XPS, LEEM-PEEM and facilities for materials structural characterizations like HR-TEM with environmental option. The center has also a nanotechnological platform with a 250 m^2 clean room and equipped with numerous nanofabrication facilities and electrical characterizations. The research group ‘Si(Ge)-based Heterostructures’ at CINaM is equipped with a unique growth system consisting of two growth chambers, MBE and CVD, which are connected in high vacuum. In situ surface characterizations such as Auger spectroscopy and differentially-pumped RHEED technique are available, allowing an in situ and real time probing of the thin film growth process. Located in the PACA region, we also get access to the characterization platform (CIMPACA) where numerous characterization tools such as m-Raman, SIMS, Laser Assisted Atom Probe (LAAP) are useful for this project.

Highly motivated candidates in experimental physics with a Master degree (or equivalent) in condensed matter physics or materials science. A prior experience in physical or chemical vapor deposition growth would be appreciated. A strong involvement in the maintenance of the MBE chamber will be expected. Qualities such as pragmatism, professionalism, taste for teamwork, but also autonomy are expected. A good English level will be appreciated.