Magnetic Field Splitting of the Spin Resonance in ${\mathrm{CeCoIn}}_{5}$

Magnetic Field Splitting of the Spin Resonance in ${CeCoIn}_{5}$

C. Stock, C. Broholm, Y. Zhao, F. Demmel, H. J. Kang, K. C. Rule, and C. Petrovic

Phys. Rev. Lett. 109, 167207 – Published 17 October 2012

Abstract

Neutron scattering in strong magnetic fields is used to show the spin resonance in superconducting ${CeCoIn}_{5}$ ( $T_{c} = 2.3 K$ ) is a doublet. The underdamped resonance ( $ℏ Γ = 0.069 \pm 0.019 meV$ ) Zeeman splits into two modes at $E_{\pm} = ℏ Ω_{0} \pm α μ_{B} μ_{0} H$ with $α = 0.96 \pm 0.05$ . A linear extrapolation of the lower peak reaches zero energy at $11.2 \pm 0.5 T$ , near the critical field for the incommensurate “ $Q$ phase.” Kenzelmann et al. [Science 321, 1652 (2008)] This, taken with the integrated weight and polarization of the low-energy mode ( $E_{-}$ ), indicates that the $Q$ phase can be interpreted as a Bose condensate of spin excitons.

Received 2 March 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.167207

Authors & Affiliations

C. Stock^1,2, C. Broholm^3,1, Y. Zhao⁴, F. Demmel⁵, H. J. Kang¹, K. C. Rule⁶, and C. Petrovic⁷

¹NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
²Indiana University, 2401 Milo B. Sampson Lane, Bloomington, Indiana 47404, USA
³Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
⁴Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
⁵ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot, OX11 0QX, United Kingdom
⁶Helmholtz Zentrum Berlin, D-14109, Berlin, Germany
⁷Condensed Matter Physics, Brookhaven National Laboratory, Upton, New York 11973, USA