N. Peter Armitage
- Courses5
- Reviews6
- School: Johns Hopkins University
- Campus:
- Department: Physics
- Email address: Join to see
- Phone: Join to see
-
Location:
3400 N Charles St
Baltimore, MD - 21218 - Dates at Johns Hopkins University: January 2012 - June 2017
- Office Hours: Join to see
Biography
Johns Hopkins University - Physics
Experience
UCLA
Postdoctoral Fellow
N. Peter worked at UCLA as a Postdoctoral Fellow
Johns Hopkins University
Professor
N. Peter worked at Johns Hopkins University as a Professor
Education
Stanford University
Phd.
Rutgers, The State University of New Jersey-New Brunswick
BS
Publications
Singlet-triplet excitations and long range entanglement in the spin-orbit liquid candidate FeSc2S4
Physical Review Letters
Theoretical models of the spin-orbital liquid (SOL) FeSc2S4 have predicted it to be in close proximity to a quantum critical point separating a spin-orbital liquid phase from a long-range ordered magnetic phase. Here, we examine the magnetic excitations of FeSc2S4 through time-domain terahertz spectroscopy under an applied magnetic field. At low temperatures an excitation emerges that we attribute to a singlet-triplet excitation from the SOL ground state. A three-fold splitting of this excitation is observed as a function of applied magnetic field. As singlet-triplet excitations are forbidden in inversion symmetric pure spin systems, our results demonstrate the non-trivial character of the entangled spin-orbital singlet ground state. Using experimentally obtained parameters we compare to existing theoretical models to determine FeSc2S4's proximity to the quantum critical point. In the context of these models, we estimate that the characteristic length of the singlet correlations to be ξ/(a/2)≈8.2 (where a/2 is the nearest neighbor lattice constant) which establishes FeSc2S4 as a SOL with long-range entanglement.
