| 1. |
- Edwards, B., et al.
(författare)
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Giant valleyZeeman coupling in the surface layer of an intercalated transition metal dichalcogenide
- 2023
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 22:4, s. 459-465
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Tidskriftsartikel (refereegranskat)abstract
- Spin–valley locking is ubiquitous among transition metal dichalcogenides with local or global inversion asymmetry, in turn stabilizing properties such as Ising superconductivity, and opening routes towards ‘valleytronics’. The underlying valley–spin splitting is set by spin–orbit coupling but can be tuned via the application of external magnetic fields or through proximity coupling. However, only modest changes have been realized to date. Here, we investigate the electronic structure of the V-intercalated transition metal dichalcogenide V1/3NbS2 using microscopic-area spatially resolved and angle-resolved photoemission spectroscopy. Our measurements and corresponding density functional theory calculations reveal that the bulk magnetic order induces a giant valley-selective Ising coupling exceeding 50 meV in the surface NbS2 layer, equivalent to application of a ~250 T magnetic field. This energy scale is of comparable magnitude to the intrinsic spin–orbit splittings, and indicates how coupling of local magnetic moments to itinerant states of a transition metal dichalcogenide monolayer provides a powerful route to controlling their valley–spin splittings.
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| 2. |
- Marques, Carolina A., et al.
(författare)
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Spin-orbit coupling induced Van Hove singularity in proximity to a Lifshitz transition in Sr4Ru3O10
- 2024
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Ingår i: npj Quantum Materials. - 2397-4648. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Van Hove singularities (VHss) in the vicinity of the Fermi energy often play a dramatic role in the physics of strongly correlated electron materials. The divergence of the density of states generated by VHss can trigger the emergence of phases such as superconductivity, ferromagnetism, metamagnetism, and density wave orders. A detailed understanding of the electronic structure of these VHss is therefore essential for an accurate description of such instabilities. Here, we study the low-energy electronic structure of the trilayer strontium ruthenate Sr4Ru3O10, identifying a rich hierarchy of VHss using angle-resolved photoemission spectroscopy and millikelvin scanning tunneling microscopy. Comparison of k-resolved electron spectroscopy and quasiparticle interference allows us to determine the structure of the VHss and demonstrate the crucial role of spin-orbit coupling in shaping them. We use this to develop a minimal model from which we identify a mechanism for driving a field-induced Lifshitz transition in ferromagnetic metals.
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| 3. |
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| 4. |
- Buchberger, Igor, 1983-
(författare)
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Strings, Gravitons, and Effective Field Theories
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns a range of aspects of theoretical physics. It is composed of two parts. In the first part we motivate our line of research, and introduce and discuss the relevant concepts. In the second part, four research papers are collected. The first paper deals with a possible extension of general relativity, namely the recently discovered classically consistent bimetric theory. In this paper we study the behavior of perturbations of the metric(s) around cosmologically viable background solutions. In the second paper, we explore possibilities for particle physics with low-scale supersymmetry. In particular we consider the addition of supersymmetric higher-dimensional operators to the minimal supersymmetric standard model, and study collider phenomenology in this class of models. The third paper deals with a possible extension of the notion of Lie algebras within category theory. Considering Lie algebras as objects in additive symmetric ribbon categories we define the proper Killing form morphism and explore its role towards a structure theory of Lie algebras in this setting. Finally, the last paper is concerned with the computation of string amplitudes in four dimensional models with reduced supersymmetry. In particular, we develop general techniques to compute amplitudes involving gauge bosons and gravitons and explicitly compute the corresponding three- and four-point functions. On the one hand, these results can be used to extract important pieces of the effective actions that string theory dictates, on the other they can be used as a tool to compute the corresponding field theory amplitudes.
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| 5. |
- Knauth, K, et al.
(författare)
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Renal cell carcinoma risk in type 2 von Hippel-Lindau disease correlates with defects in pVHL stability and HIF-1 alpha interactions
- 2006
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 25:3, s. 370-377
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Tidskriftsartikel (refereegranskat)abstract
- The von Hippel-Lindau (VHL) tumor suppressor protein is the substrate binding subunit of the CBC(VHL) E3 ubiquitin ligase complex. Mutations in the VHL gene cause a variety of tumors with complex genotype/phenotype correlations. Type 2A and type 2B VHL disease are characterized by a low or high risk of renal cell carcinoma, respectively. To investigate the molecular basis underlying the difference between disease types 2A and 2B, we performed a detailed biochemical analysis of the two most frequent type 2A mutations, Y98 H and Y112 H, in comparison to type 2B mutations in the same residues, Y98N and Y112N. While none of these mutations affected the assembly of CBC(VHL) complexes, the type 2A mutant proteins exhibited higher stabilities at physiological temperature. Moreover, the type 2A mutant proteins possessed higher binding affinities for the key cellular substrate, hypoxia-inducible transcription factor 1 (HIF-1alpha). Consistent with these results, type 2A but not type 2B mutant VHL proteins retained significant ubiquitin ligase activity towards HIF-1alpha in vitro. We propose that this residual ubiquitin ligase activity is sufficient to suppress renal cell carcinogenesis in vivo.
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