Anomalous excitations of atomically crafted quantum magnets

Abstract

High energy resolution spectroscopic studies of quantum magnets have proven to be extremely valuable in directly accessing magnetodynamics quantities, such as energy barriers, magnetic interactions, lifetime of excited states and fluctuations at the most fundamental level. Here, we explore the existence of a new 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 to be 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 studied nanostructures. We additionally map the evolution of the conductance peak in artificial nanostructures crafted atom-by-atom, which show clear evidence of spin-coupled behavior. The results are rationalized in terms of a non-collinear 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.

Main manuscript including supplementary material

References in corpus (12)

• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Spin qubits with electrically gated polyoxometalate molecules
• Protection of excited spin states by a superconducting energy gap
• Dynamical magnetic excitations of nanostructures from first-principles
• On the preparation and electronic properties of clean superconducting Nb(110) surfaces
• Relativistic dynamical spin excitations of magnetic adatoms
• Transverse dynamical magnetic susceptibilities from regular static density functional theory: Evaluation of damping and g-shifts of spin-excitations
• Long range and highly tunable interaction between local spins coupled to a superconducting condensate
• Non-Kondo zero-bias anomaly in quantum wires
• Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors
• Renormalization of electron self-energies via their interaction with spin excitations: A first-principles investigation
• Tuning paramagnetic spin-excitations of single adatoms

Cited by in corpus (6)

• Non-Majorana modes in diluted spin chains proximitized to a superconductor
• Coexistence of Antiferromagnetism and Superconductivity in Mn/Nb(110)
• Density functional Bogoliubov-de Gennes analysis of superconducting Nb and Nb(110) surfaces
• Spin-resolved spectroscopic evidence for spinarons in Co adatoms
• Increased localization of Majorana modes in antiferromagnetic chains on superconductors
• Spin and electronic excitations in $4f$ atomic chains on Au(111) substrates