Self-induced spin glass state in elemental and crystalline neodymium

Abstract

Spin glasses are a highly complex magnetic state of matter intricately linked to spin frustration and structural disorder. They exhibit no long-range order and exude aging phenomena, distinguishing them from quantum spin liquids. We report a previously unknown type of spin glass state, the spin-Q glass, observable in bulk-like crystalline metallic neodymium thick films. Using spin-polarized scanning tunneling microscopy combined with ab initio calculations and atomistic spin-dynamics simulations, we visualized the variations in atomic-scale noncolinear order and its response to magnetic field and temperature. We quantified the aging phenomena relating the glassiness to crystalline symmetry and the energy landscape. This result not only resolves the long-standing debate of the magnetism of neodymium, but also suggests that glassiness may arise in other magnetic solids lacking extrinsic disorder.

Electronic and Magnetic Properties of Building Blocks of Mn and Fe Atomic Chains on Nb(110)

“…This suggests that in very long chains, sections with different spin spiral periods and even opposite chiralities may alternate at finite temperature if the system is unable to find the global energy minimum. Such a state would be similar to the spin glass state recently investigated on the (0001) surface of Nd in [ 27 ]. If all the interactions are taken into account up to the 7th neighbor of the middle spin, the maximum of is obtained at , meaning that the wavelength of the spin spiral should be .…”

“…If the Fourier transform of the isotropic interactions has pockets with flat dispersion relation in the Brillouin zone, magnetic domains with different wave vectors can form. This was recently demonstrated by Kamber and coworkers [ 27 ] on the (0001) surface of crystalline Nd. Together with the aging effect—where the magnetic state depends on its history, this points toward the formation of a spin glass state, usually observed in disordered materials rather than crystalline systems with long-range periodicity.…”

“…We also explore the connection between the local density of states and the decomposition of the isotropic Heisenberg exchange interaction into atomic orbitals, for different relative alignments and coordination numbers of the atoms. While most chains are found to be collinear ferromagnetic or antiferromagnetic, Fe chains on Nb(110) along the [110] direction exhibit a spin-spiral ground state with a flat dispersion relation due to the frustration of the isotropic couplings, similar to the foundings for Nd in [27].…”

“…The electronic and magnetic structure of the considered and similar metallic systems can usually be well described by using the local density approximation (LDA) [ 9 , 10 , 26 , 27 ] or the generalized gradient approximation (GGA) [ 8 ] within DFT.…”

A scanning tunneling microscope capable of electron spin resonance and pump–probe spectroscopy at mK temperature and in vector magnetic field

“…Here, based on a recent ultra-high vacuum (UHV) spinresolved DR-STM operational at mK temperatures and in a vector magnetic field, 18,37 we detail the implementation and performance of both ESR and pump-probe methods at mK temperatures in this system. We demonstrate the ESR-STM operation in two different modes, namely, the frequency sweep ( f -sweep) and magnetic field sweep (B-sweep) mode.…”