Possible Anisotropic $s-f$ Hybridization in a Cubic Heavy-Fermion Compound: ${\mathrm{CeIn}}_1{\mathrm{Sn}}_2$

Polarized neutron scattering measurements on a single crystal of composition ${\mathrm{CeIn}}_1{\mathrm{Sn}}_2$ show a broad, single-ion, spectral response centered on a characteristic energy of $\sim 9\pm 1\mathrm{meV}$ at the zone boundary point $(001.5)$. The zone center spectral response is closely similar in form but has a slightly reduced amplitude, smaller by some 20%. Constant-$\omega$ scans show that these intensity modulations, of amplitude $\sim 10\%$, resembling intersite antiferromagnetic correlations, are superimposed on a mean variation that follows the ${\mathrm{Ce}}^{3+}$, $4f^1$, single-ion form factor, and are tentatively attributed to $\mathbf{q}$-dependent hybridization of the localized $4f$ state with the conduction electrons.

Figure 1

Paramagnetic spectral response from the ${\mathrm{CeIn}}_1{\mathrm{Sn}}_2$ sample at 5 K at the ZB point $(001.5)$. The continuous curve represents a fit to the Kuramoto and Müller-Hartmann spectral function [13] and the dashed curve represents the Lorentzian spectral fit. Parameters resulting from the fits are given in the text.

Figure 2

Constant-energy scans along $[00\xi ]$ at (a) $\omega =13\mathrm{meV}$ and (b) $\omega =18\mathrm{meV}$, performed on the ${\mathrm{CeIn}}_1{\mathrm{Sn}}_2$ single crystal sample at 5 K. The data also show the as-measured spin-flip scattering (${\sigma }_{\Vert Q}^{\mathrm{SF}}$) parallel to the scattering vector $Q$ (triangles) which consists of the magnetic cross-section, plus incoherent and background scattering contributions. The continuous curve is the ${\mathrm{Ce}}^{3+}$ form factor through the data representing the magnetic scattering (squares) given by $2({\sigma }_{\Vert Q}^{\mathrm{SF}}-{\sigma }_{\perp Q}^{\mathrm{SF}})$.