Search results for "Rust"

Decoupling lattice and magnetic instabilities in frustrated CuMnO$_2$

2021

The $A$MnO$_{2}$ delafossites ($A$=Na, Cu), are model frustrated antiferromagnets, with triangular layers of Mn$^{3+}$~spins. At low temperatures ($T_{N}$=65 K), a $C2/m \rightarrow P\overline{1}$ transition is found in CuMnO$_2$, which breaks frustration and establishes magnetic order. In contrast to this clean transition, $A$=Na only shows short-range distortions at $T_N$. Here we report a systematic crystallographic, spectroscopic, and theoretical investigation of CuMnO$_2$. We show that, even in stoichiometric samples, non-zero anisotropic Cu displacements co-exist with magnetic order. Using X-ray/neutron diffraction and Raman scattering, we show that high pressures acts to decouple the…

Quantum magnetism of spin-ladder compounds with trapped-ion crystals

2012

Abstract The quest for experimental platforms that allow for the exploration, and even control, of the interplay of low dimensionality and frustration is a fundamental challenge in several fields of quantum many-body physics, such as quantum magnetism. Here, we propose the use of cold crystals of trapped ions to study a variety of frustrated quantum spin ladders. By optimizing the trap geometry, we show how to tailor the low dimensionality of the models by changing the number of legs of the ladders. Combined with a method for selectively hiding ions provided by laser addressing, it becomes possible to synthesize stripes of both triangular and Kagome lattices. Besides, the degree of frustrat…

Properties of dirty two-band superconductors with repulsive interband interaction: Normal modes, length scales, vortices, and magnetic response

2018

Disorder in two-band superconductors with repulsive interband interaction induces a frustrated competition between the phase-locking preferences of the various potential and kinetic terms. This frustrated interaction can result in the formation of an $s+is$ superconducting state, that breaks the time-reversal symmetry. In this paper we study the normal modes and their associated coherence lengths in such materials. We especially focus on the consequences of the soft modes stemming from the frustration and time-reversal-symmetry breakdown. We find that two-bands superconductors with such impurity-induced frustrated interactions display a rich spectrum of physical properties that are absent i…

EctoparasiticArgulus coregoni(Crustacea: Branchiura) hedge their bets - studies on egg hatching dynamics

2004

Unpredictability in the temporal availability of susceptible hosts is likely to act as a selection pressure affecting the life history strategies of parasites. In highly variable environments the future of the lineage can be secured by spreading the risk, for example, by producing descendants that differ in their timing of emergence. Counter to this, in predictable environments a single “best-adapted” phenotype is expected. We asked whether ectoparasitic Argulus coregoni egg hatching pattern can be explained as a genetically canalized individual trait; an instance of phenotypic plasticity or bet-hedging. We collected egg clutches laid by individual A. coregoni females in early and late repr…

2013

Are dreams subjective experiences during sleep? Is it like something to dream, or is it only like something to remember dreams after awakening? Specifically, can dream reports be trusted to reveal what it is like to dream, and should they count as evidence for saying that dreams are conscious experiences at all? The goal of this article is to investigate the relationship between dreaming, dream reporting and subjective experience during sleep. I discuss different variants of philosophical skepticism about dream reporting and argue that they all fail. Consequently, skeptical doubts about the trustworthiness of dream reports are misguided, and for systematic reasons. I suggest an alternative,…

Opinia prawna na temat beneficjenta rzeczywistego w przypadku spółki kapitałowej, której jedynym (100%) udziałowcem czy akcjonariuszem jest zakon, bą…

2020

Celem niniejszej opinii prawnej jest udzielenie odpowiedzi na pytanie: Kto jest beneficjentem rzeczywistym w przypadku spółki kapitałowej, której jedynym (100%) udziałowcem czy akcjonariuszem jest zakon bądź jego jednostka organizacyjna (prowincja zakonna, opactwo, klasztor niezależny, dom zakonny)? Przeprowadzone analizy przepisów prawa polskiego i prawa kanonicznego prowadzą do wniosku, że w przypadku spółki kapitałowej, której jedynym (100%) udziałowcem czy akcjonariuszem jest zakon bądź jego jednostka organizacyjna (prowincja zakonna, opactwo, klasztor niezależny, dom zakonny) beneficjentem rzeczywistym jest właściwy wyższy przełożony tego zakonu oraz członkowie jego rady. Osoby te speł…

Cutoff dependence of the thrust peak position in the dipole shower

2020

We analyse the dependence of the peak position of the thrust distribution on the cutoff value in the Nagy-Soper dipole shower. We compare the outcome of the parton shower simulations to a relation of the dependence from an analytic computation, derived within soft-collinear effective theory. We show that the result of the parton shower simulations and the analytic computation are in good agreement.

Elementary triangles in a 2D binary colloidal glass former

2005

Particle positions of a two-dimensional (2D) binary colloidal glass former were measured video-microscopically. Local density-optimized structures of triangles of nearest-neighboring particles (TNNP) were found from the shortest pair-distances. These are referred to as elementary triangles (ET)—exactly one for each 3-particle combination of the two kinds of colloids. Clustering of ET-like TNNP implies larger distances between two particles, which generate the near-zone maxima in the pair-distribution functions. Tiling mismatches of different kinds of ET create structural frustrations. Increasing combination possibilities for the tiling of the different ET lead to the loss of long-range orde…

Skyrmions and multi-sublattice helical states in a frustrated chiral magnet

2016

We investigate the existence and stability of skyrmions in a frustrated chiral ferromagnet by considering the competition between ferromagnetic (FM) nearest-neighbour (NN) interaction ($J_1$) and antiferromagnetic (AFM) next-nearest-neighbour (NNN) interaction ($J_2$). Contrary to the general wisdom that long-range ferromagnetic order is not energy preferable under frustration, the skyrmion lattice not only exists but is even stable for a large field range when $J_2 \leq J_1$ compared with frustration-free systems. We defend that the enlargement of stability window of skyrmions is a consequence of the reduced effective exchange interaction caused by the frustration. A multi-sublattice helic…

Discriminating antiferromagnetic signatures in systems of ultracold fermions by tunable geometric frustration

2013

Recently, it has become possible to tune optical lattices continuously between square and triangular geometries. We compute thermodynamics and spin correlations in the corresponding Hubbard model using a determinant quantum Monte Carlo technique and show that the frustration effects induced by the variable hopping terms can be clearly separated from concomitant bandwidth changes by a proper rescaling of the interaction. An enhancement of the double occupancy by geometric frustration signals the destruction of nontrivial antiferromagnetic correlations at weak coupling and entropy $s\ensuremath{\lesssim}\mathrm{ln}(2)$ (and restores Pomeranchuk cooling at strong frustration), paving the way t…