skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Applying Unconventional Spectroscopies to the Single‐Molecule Magnets, Co(PPh 3 ) 2 X 2 (X=Cl, Br, I): Unveiling Magnetic Transitions and Spin‐Phonon Coupling
Title: Applying Unconventional Spectroscopies to the Single‐Molecule Magnets, Co(PPh 3 ) 2 X 2 (X=Cl, Br, I): Unveiling Magnetic Transitions and Spin‐Phonon Coupling
Abstract Large separation of magnetic levels and slow relaxation in metal complexes are desirable properties of single‐molecule magnets (SMMs). Spin‐phonon coupling (interactions of magnetic levels with phonons) is ubiquitous, leading to magnetic relaxation and loss of memory in SMMs and quantum coherence in qubits. Direct observation of magnetic transitions and spin‐phonon coupling in molecules is challenging. We have found that far‐IR magnetic spectra (FIRMS) of Co(PPh3)2X2(Co‐X; X=Cl, Br, I) reveal rarely observed spin‐phonon coupling as avoided crossings between magnetic andu‐symmetry phonon transitions. Inelastic neutron scattering (INS) gives phonon spectra. Calculations using VASP and phonopy programs gave phonon symmetries and movies. Magnetic transitions among zero‐field split (ZFS) levels of theS=3/2 electronic ground state were probed by INS, high‐frequency and ‐field EPR (HFEPR), FIRMS, and frequency‐domain FT terahertz EPR (FD‐FT THz‐EPR), giving magnetic excitation spectra and determining ZFS parameters (D, E) andgvalues. Ligand‐field theory (LFT) was used to analyze earlier electronic absorption spectra and give calculated ZFS parameters matching those from the experiments. DFT calculations also gave spin densities inCo‐X, showing that the larger Co(II) spin density in a molecule, the larger its ZFS magnitude. The current work reveals dynamics of magnetic and phonon excitations in SMMs. Studies of such couplings in the future would help to understand how spin‐phonon coupling may lead to magnetic relaxation and develop guidance to control such coupling.  more » « less
Award ID(s):
1900296 1824267 2004732
PAR ID:
10233288
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Chemistry – A European Journal
Volume:
27
Issue:
43
ISSN:
0947-6539
Format(s):
Medium: X Size: p. 11110-11125
Size(s):
p. 11110-11125
Sponsoring Org:
National Science Foundation
More Like this
  1. (, Wuji huaxue xuebao)
    Trigonal bipyramidal Ni(II) complex [Ni(Me6tren)Cl](ClO4) (1, Me6tren = tris[2-(dimethylamino)ethyl]amine) has recently been shown by Ruamps and coworkers to possess large, uniaxial magnetic anisotropy (J. Am. Chem. Soc. 2013, 135, 3017). Their HF-EPR studies gave rhombic zero-field-splitting (ZFS) parameter E = 1.56(5) cm-1 for 1. However, the axial ZFS parameter D has not been determined. We have used far-IR magnetic spectroscopy (FIRMS) at 0-17.5 T and 5 K to probe the magnetic transitions between the MS = 1 and MS = 0 states of the ground spin state S = 1 in 1. Direct observation of the transitions between Zeeman-split states in FIRMS give axial ZFS parameter D = -110.7(3) cm-1. Hirshfeld surface analysis of the crystal structure of 1 has been performed, revealing the interactions between the cation and anion in a molecule of 1 as well as among the molecules of 1 in crystals. 
    more » « less
  2. ; ; (, Dalton Transactions)
    Magnetic anisotropy and spin–phonon coupling are key properties of single-molecule magnets. The use of far-IR and Raman magneto-spectroscopies (FIRMS and RaMS), and inelastic neutron scattering (INS) to determine the magnetic properties is highlighted. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Materials)
    Abstract The Rashba effect enables control over the spin degree of freedom, particularly in polar materials where the polar symmetry couples to Rashba‐type spin splitting. The exploration of this effect, however, has been hindered by the scarcity of polar materials exhibiting the bulk‐Rashba effect and rapid spin‐relaxation effects dictated by the D'yakonov–Perel mechanism. Here, a polar LiNbO3‐typeR3cphase of Bi1‐xIn1+xO3withx≈0.15–0.24 is stabilized via epitaxial growth, which exhibits a bulk‐Rashba effect with suppressed spin relaxation as a result of its unidirectional spin texture. As compared to the previously observed non‐polarPnmaphase, this polar phase exhibits higher conductivity, reduced bandgap, and enhanced dielectric and piezoelectric responses. Combining first‐principles calculations and multimodal magnetotransport measurements, which reveal weak (anti)localization, anisotropic magnetoresistance, planar‐Hall effect, and nonreciprocal charge transport, a bulk‐Rashba effect without rapid spin relaxation is demonstrated. These findings offer insights into spin‐orbit coupling physics within polar oxides and suggest potential spintronic applications. 
    more » « less
  4. ; (, Small)
    Abstract Here, the observation of spin‐polarized emission for the Au25(SC8H9)18monolayer‐protected cluster (MPC) is reported. Variable‐temperature variable‐field magnetic circular photoluminescence (VTV‐MCPL) measurements are combined with VT‐PL spectroscopy to provide state‐resolved characterization of the transient electronic structure and spin‐polarized electron‐hole recombination dynamics of Au25(SC8H9)18. Through analysis of VTV‐MCPL measurements, a low energy (1.64 eV) emission peak is assigned to intraband relaxation between core‐metal‐localized superatom‐D to ‐P orbitals. Two higher energy interband components (1.78 eV, 1.94 eV) are assigned to relaxation from superatom‐D orbitals to states localized to the inorganic semirings. For both intraband superatom‐based or interband relaxation mechanisms, the extent of spin‐polarization, quantified as the degree of circular polarization (DOCP), is determined by state‐specific electron‐vibration coupling strengths and energy separations of bright and dark electronic fine‐structure levels. At low temperatures (<60 K), metal–metal superatom‐based intraband transitions dominate the global PL emission. At higher temperatures (>60 K), interband ligand‐based emission is dominant. In the low‐temperature PL regime, increased sample temperature results in larger global PL intensity. In the high‐temperature regime, increased temperature quenches interband radiative recombination. The relative intensity for each PL mechanism is discussed in terms of state‐specific electronic‐vibrational coupling strengths and related to the total angular momentum, quantified by Landég‐factors. 
    more » « less
  5. ; ; ; ; ; ; ; ; (, Advanced Physics Research)
    Abstract Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect (THE), a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn2‐xZnxSb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high‐Zn (x > 0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low‐Zn (x < 0.6) samples show an opposite trend. The coexistence of those distinct temperature dependencies for THE suggests very different magnetic interactions/structures for different compositions and underscores the strong coupling between magnetism and transport in Mn2‐xZnxSb. The findings contribute to understanding topological magnetism in centrosymmetric tetragonal lattices, establishing Mn2‐xZnxSb as a unique platform for exploring tunable transport effects and opening avenues for further exploration in the realm of spintronics. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email