Anomalous excitations of atomically crafted quantum magnets

Abstract

High–energy resolution spectroscopic studies of quantum magnets proved extremely valuable in accessing magnetodynamics quantities, such as energy barriers, magnetic interactions, and lifetime of excited states. Here, we investigate a previously unexplored flavor of low-energy spin excitations for quantum spins coupled to an electron bath. In sharp contrast to the usual tunneling signature of two steps symmetrically centered around the Fermi level, we find a single step in the conductance. Combining time-dependent and many-body perturbation theories, magnetic field–dependent tunneling spectra are explained as the result of an interplay between weak magnetic anisotropy energy, magnetic interactions, and Stoner-like electron-hole excitations that are strongly dependent on the magnetic states of the nanostructures. The results are rationalized in terms of a noncollinear magnetic ground state and the dominance of ferro- and antiferromagnetic interactions. The atomically crafted nanomagnets offer an appealing model for the exploration of electrically pumped spin systems.

Non-Majorana modes in diluted spin chains proximitized to a superconductor

“…3 D , G , and J ), the data reveal a scenario where adatoms are essentially decoupled, as evidenced by the very small differences visible in the spectroscopy once comparing data acquired inside the chain and at the chain end. Interestingly, a distinct boundary behavior at zero energy is also found in the metallic regime ( 41 ) ( SI Appendix , Note 6 and Discussion below).…”

Non-Majorana modes in diluted spin chains proximitized to a superconductor

“…Our results reveal that, in agreement with expectations, the strong accumulation of spectral weight predominantly localized at the end of the chains becomes very weak for distances of approximately 1.45 nm. Interestingly, a distinct boundary behavior at zero-energy is also found in the metallic regime 36 (see Supplementary Note 5 and discussion below).…”

Superconductivity in Nb: Impact of Temperature, Dimensionality and Cooper-Pairing

“…In this context, the Bogoliubovde Gennes (BdG) method [14][15][16][17] is an elegant mean-field approximation that relies upon Bogoliubov-Valatin transformations that take the Hamiltonian from a particle space into a particle-hole one-a framework that has been frequently used, see for example Refs. [18][19][20][21][22][23][24][25][26][27][28]. Nowadays, several methods based on a realistic description of the electronic structure of materials are capable of treating fundamental aspects related to superconductivity.…”