Using low energy Muons spin rotation spectroscopy, measurement of dc/ac magnetic susceptibility and measurement of capacitance, we show that epitaxially grown Nd-based perovskite high entropy oxides exhibit significant ferromagnetism, spin-glass behaviour, high dielectric constant at RT and a temperature-dependent ferroelectric hysteresis that are intricately coupled to each other. X-ray...
The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. Recently, the theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials. Here we provide experimental evidence of room-temperature magnetization in the...
In ferroelectric LiNbO3, THz light couples with low-frequency optical phonons and form phonon polaritons. Recent studies have shown that is possible to probe nonlinearities at specific points along the phonon-polariton dispersion curve with different probe wavelengths after broadband excitation with strong THz transients. However, extensive measurements of lattice anharmonicities in LiNbO3 are...
Using the Sierpinski gasket as an example, we theoretically study the properties of fractal superconductors. We focus on the phenomenon of s-wave superconductivity in the Hubbard model with attractive on-site potential and employ the Bogoliubov-de Gennes approach. For the case of the Sierpinski gasket, we demonstrate that fractal geometry of the underlying crystalline lattice can be strongly...
The physics of charge order in high-temperature superconducting cuprates is still largely unexplained. Recent experiments revealed the presence of strong quantum fluctuations, whose doping and temperature dependence suggest the closeness to a quantum critical point and a relation to the strange-metal phase. We used ultra-high-resolution Resonant Inelastic X-ray Scattering in combination with...
Blue Bronze ($K_{0.3}MoO_3$) is a quasi 1D material exhibiting a charge-density-wave (CDW) with a periodic lattice distortion (PLD). In a time resolved x-ray experiment at SwissFEL, we study the dynamics of the PLD by pumping $K_{0.3}MoO_3$ with short laser pulses and probing it using x-ray diffraction. We construct reciprocal space maps (RSM) of superlattice reflections at different delays....
Here, we will present the development of a novel resonant ultrasound spectroscopy (RUS) setup. Subsequently, we report our investigation of the superconducting vortex lattice of a commercially available single crystal of high purity (Nb - 99.999%). Based on our measurements, we determine the vortex lattice phase diagram, and compare it to results from electrical resistivity and neutron...
This study investigates a 2D Janus heterostructure made by combining lepidocrocite TiO2 and MoSSe, focusing on the energetic stability and change in electronic properties with respect to varied interface terminations. Using state-of-the-art density functional theory simulations, we show that TiO2-MoSSe heterostructures are energetically feasible to form. The results indicate that by varying...
Mechanical spectroscopy tests of high-purity nickel single crystal, with different lattice orientations, were performed in a forced oscillation pendulum, under high vacuum, at different frequencies. The temperature was varied from room temperature up to 500 °C. A periodic strain of amplitude 5x10−5 was applied. Internal friction spectrum reveals 3 mechanical loss peaks: P0 (transient peak), P1...
Diamond offers excellent prospects for the study of phonon transport phenomena beyond Fourier's law at room temperature. Here, we investigate heat transport properties of suspended diamond microstructures using NV centers in the diamond lattice as in-situ temperature sensors. We present diffraction-limited spatially resolved measurements of temperature across suspended cantilevers, with a...
Conventional electron transport in conductors involves diffusive scattering and interactions with lattice vibrations, resulting in Ohmic behavior. However, a distinct regime arises when electron-electron interactions induce correlated, momentum-conserving flow akin to classical fluid dynamics. Our study delves into charge hydrodynamic transport, revealing width-dependent conductivity and...
Laser induced energy transfer and dissipation in nanoparticles within a liquid environment are of specific interest due to their relevance in photochemical and biomedical applications. In particular a quantitative understanding of electron-phonon coupling (EPC) is required for determining the life-time of hot electrons and heat generation. Currently, most related studies are based on optical...
For the first time we demonstrate an ultrafast scanning electron (USEM) microscope with electron-beam-induced current (EBIC) capability. This novel technique allows for in-situ observation of depletion layers in fast semiconductor devices. We demonstrate micrometer spatial and picosecond temporal resolution on an avalanche photodiode. EBIC is a well established method in semiconductor...
Light-matter interaction can be strongly enhanced by confining the electric
field in optical cavities. These require a well-suited stacking of reflecting and
transparent materials selected for the frequency range of interest. In our study,
we target the Terahertz spectrum and have chosen the SrVO3 compound for
its high reflectivity in this frequency range. We report results on the...
A method for increasing the dynamical range of scanning tunneling microscopes (STM) is introduced. We first transform the nonlinear current-voltage characteristic into a time-dependent current via AC excitation and then actively cancel dominant current harmonics using a driven compensating capacitor. The placement of the compensating capacitor allows us to create removal currents precisely...
We introduce an innovative analytical framework for analyzing the interaction of charged perturbations with a three-dimensional (3D) half-infinite conductive space. Our method merges the quasi-3D expansion of the one-dimensional (1D) Kronig-Penney metal with Tamm's surface states, offering a comprehensive analysis tool for multipole molecule-conductive surface interactions. Validated against...
Rare-earth pyrochlores frequently exhibit spin ice correlations and, therefore, can potentially host quantum spin ice (QSI) phases. In these systems, the spin-orbital ground state doublet can be represented as an effective pseudo-spin 1/2. In addition to dipolar moments, multipoles are allowed, which can stabilise ice or ordered phases, or introduce quantum fluctuations on a dipolar spin ice...
Predicting the phase diagram of interacting quantum many-body systems is a central problem in quantum matter. Here, we show that a Lee-Yang method, combined with numerical quantum many-body methods such as matrix product states and neural network quantum states, can be used to investigate quantum phase transitions and predict the critical points of correlated spin and fermion models....
Hybrid Tensor Networks (hTNs) offer a promising solution for encoding variational quantum states beyond the capabilities of efficient classical methods or noisy quantum computers alone. However, their practical usefulness and many operational aspects of hTN-based algorithms have not been thoroughly investigated yet. In this contribution, we introduce a novel algorithm to perform ground state...
We utilize known theoretical results about many-body quantum critical dynamics to benchmark quantum hardware and various error mitigation techniques on up to 133 qubits. In particular, we benchmark against known universal scaling laws in the Hamiltonian simulation of a time-dependent transverse-field Ising Hamiltonian. Incorporating basic error mitigation and suppression, our study shows...
The recent experimental observations of fractional Chern insulators in moiré systems without an applied magnetic field prompt the question of whether their time-reversal invariant generalization, fractional topological insulators (FTIs), can also be realized in these platforms. Using comprehensive exact diagonalization calculations on twisted bilayer MoTe2 at nu=-4/3 and an idealized Landau...
Quantum critical points (QCPs) are windows to fundamental quantum mechanical phenomena associated with universal behaviour. Recently, antisymmetric spin-orbit coupling in noncentrosymmetric systems was suggested to protect ferromagnetic QCPs. A dense Kondo lattice CeSi$_{2-δ}$, crystallising in a centrosymmetric structure, exhibits ferromagnetic order when Si is replaced with Ag. We report...
