Gesa-R. Siemann
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View article: Line shapes in time- and angle-resolved photoemission spectroscopy explored by machine learning
Line shapes in time- and angle-resolved photoemission spectroscopy explored by machine learning Open
Time- and angle-resolved photoemission spectroscopy is a powerful technique for investigating the dynamics of excited carriers in quantum materials. Typically, data analysis proceeds via the inspection of time distribution curves (TDCs), w…
View article: Line shapes in time- and angle-resolved photoemission spectroscopy explored by machine learning
Line shapes in time- and angle-resolved photoemission spectroscopy explored by machine learning Open
Time- and angle-resolved photoemission spectroscopy is a powerful technique for investigating the dynamics of excited carriers in quantum materials. Typically, data analysis proceeds via the inspection of time distribution curves (TDCs), w…
View article: Dichotomy of electron-phonon interactions in the delafossite PdCoO$_2$: From weak bulk to polaronic surface coupling
Dichotomy of electron-phonon interactions in the delafossite PdCoO$_2$: From weak bulk to polaronic surface coupling Open
The metallic delafossites host ultra-high mobility carriers in the bulk, while at their polar surfaces, intrinsic electronic reconstructions stabilise markedly distinct electronic phases, from charge-disproportionated insulators, to Rashba…
View article: Avoided metallicity in a hole-doped Mott insulator on a triangular lattice
Avoided metallicity in a hole-doped Mott insulator on a triangular lattice Open
View article: Chemical Trends of the Bulk and Surface Termination-Dependent Electronic Structure of Metal-Intercalated Transition Metal Dichalcogenides
Chemical Trends of the Bulk and Surface Termination-Dependent Electronic Structure of Metal-Intercalated Transition Metal Dichalcogenides Open
The addition of metal intercalants into the van der Waals gaps of transition metal dichalcogenides has shown great promise as a method for controlling their functional properties. For example, chiral helimagnetic states, current-induced ma…
View article: Spin-orbit coupling induced Van Hove singularity in proximity to a Lifshitz transition in Sr4Ru3O10
Spin-orbit coupling induced Van Hove singularity in proximity to a Lifshitz transition in Sr4Ru3O10 Open
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 p…
View article: Controlling the Charge Density Wave Transition in Single-Layer TiTe<sub>2<i>x</i></sub>Se<sub>2(1–<i>x</i>)</sub> Alloys by Band Gap Engineering
Controlling the Charge Density Wave Transition in Single-Layer TiTe<sub>2<i>x</i></sub>Se<sub>2(1–<i>x</i>)</sub> Alloys by Band Gap Engineering Open
Closing the band gap of a semiconductor into a semimetallic state gives a powerful potential route to tune the electronic energy gains that drive collective phases like charge density waves (CDWs) and excitonic insulator states. We explore…
View article: Avoided metallicity in a hole-doped Mott insulator on a triangular lattice
Avoided metallicity in a hole-doped Mott insulator on a triangular lattice Open
Doping of a Mott insulator gives rise to a wide variety of exotic emergent states, from high-temperature superconductivity to charge, spin, and orbital orders. The physics underpinning their evolution is, however, poorly understood. A majo…
View article: Spin-orbit coupled spin-polarised hole gas at the CrSe2-terminated surface of AgCrSe2
Spin-orbit coupled spin-polarised hole gas at the CrSe2-terminated surface of AgCrSe2 Open
In half-metallic systems, electronic conduction is mediated by a single spin species, offering enormous potential for spintronic devices. Here, using microscopic-area angle-resolved photoemission, we show that a spin-polarised two-dimensio…
View article: Covalency, correlations, and interlayer interactions governing the magnetic and electronic structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Mn</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Si</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math>
Covalency, correlations, and interlayer interactions governing the magnetic and electronic structure of Open
Mn3Si2Te6 is a rare example of a layered ferrimagnet. It has recently been shown to host a colossal angular magnetoresistance as the spin orientation is rotated from the in- to out-of-plane direction, proposed to be underpinned by a topolo…
View article: Spin-orbit coupling induced Van Hove singularity in proximity to a Lifshitz transition in Sr$_4$Ru$_3$O$_{10}$
Spin-orbit coupling induced Van Hove singularity in proximity to a Lifshitz transition in Sr$_4$Ru$_3$O$_{10}$ Open
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 n…
View article: Covalency, correlations, and inter-layer interactions governing the magnetic and electronic structure of Mn$_3$Si$_2$Te$_6$
Covalency, correlations, and inter-layer interactions governing the magnetic and electronic structure of Mn$_3$Si$_2$Te$_6$ Open
Mn$_3$Si$_2$Te$_6$ is a rare example of a layered ferrimagnet. It has recently been shown to host a colossal angular magnetoresistance as the spin orientation is rotated from the in- to out-of-plane direction, proposed to be underpinned by…
View article: Hierarchy of Lifshitz Transitions in the Surface Electronic Structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow><mml:mi>Sr</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi>RuO</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub></mml:math> under Uniaxial Compression
Hierarchy of Lifshitz Transitions in the Surface Electronic Structure of under Uniaxial Compression Open
We report the evolution of the electronic structure at the surface of the layered perovskite Sr_{2}RuO_{4} under large in-plane uniaxial compression, leading to anisotropic B_{1g} strains of ϵ_{xx}-ϵ_{yy}=-0.9±0.1%. From angle-resolved pho…
View article: Giant valley-Zeeman coupling in the surface layer of an intercalated transition metal dichalcogenide
Giant valley-Zeeman coupling in the surface layer of an intercalated transition metal dichalcogenide Open
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 v…
View article: Planar triangular <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>S</mml:mi><mml:mo>=</mml:mo><mml:mn>3</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math> magnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>AgCrSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>: Magnetic frustration, short range correlations, and field-tuned anisotropic cycloidal magnetic order
Planar triangular magnet : Magnetic frustration, short range correlations, and field-tuned anisotropic cycloidal magnetic order Open
Our studies evidence an anisotropic magnetic order below $T_N = 32$~K.\nSusceptibility data in small fields of about 1~T reveal an antiferromagnetic\n(AFM) order for $H \\perp c$, whereas for $H \\parallel c$ the data are\nreminiscent of a…
View article: The planar triangular $S=3/2$ magnet AgCrSe$_2$: magnetic frustration, short range correlations, and field tuned anisotropic cycloidal magnetic order
The planar triangular $S=3/2$ magnet AgCrSe$_2$: magnetic frustration, short range correlations, and field tuned anisotropic cycloidal magnetic order Open
Our studies evidence an anisotropic magnetic order below $T_N = 32$~K. Susceptibility data in small fields of about 1~T reveal an antiferromagnetic (AFM) order for $H \perp c$, whereas for $H \parallel c$ the data are reminiscent of a fiel…