Two-magnon processes

Fig. 83, Temperature dependence of the pSR relaxation rate in NdRhjSij. Left A single e>q>onentially relaxing signal is seen for the c-axis parallel to muon spin polarization. The rate below the Neel temperature is fitted to a two-magnon process. Right Critical behavior of the paramagnetic relaxation rate for the c-axis perpendicular to the muon spin polarization (longitudinal spin fluctuations). The insert shows a fit to a critical power law.

Fig.l. Stripe models for 1/3 doping.18 Arrows indicate correlated Ni magnetic moments circles indicate oxygen sites filled circles indicate locations of doped holes on oxygen sites. Bold dashed lines indicate positions of domain walls, while bold solid lines outline a magnetic unit cell. The two-magnon Raman process is shown also bold arrows demonstrate spins on adjacent sites and curved lines indicate broken magnetic bonds. 

Fig. 6. Diagram of the two-magnon Raman scattering process in the cuprates (a) initial antiferromagnetic spin configuration on the Cu sites (b) incident photon excitation of a spin-up Cu(3d ) hole to an intermediate-state 0(2p) orbital (c) double spin flip due to direct spin exchange between the spin-up hole on the intermediate-state 0(2p) site and a spin-down hole on a nearest-neighbor Cu site (d) hopping of a spin-down hole from the 0(2p) intermediate state to the original copper site, emitting the scattered photon.

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