Low-energy Ce spin excitations in CeFeAsO and
CeFeAsO 0.84 F 0.16

doi:10.1007/s11467-009-0077-8

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Front. Phys. ›› 2010, Vol. 5 ›› Issue (2) : 161-165. DOI: 10.1007/s11467-009-0077-8

Research articles

Low-energy Ce spin excitations in CeFeAsO and CeFeAsO 0.84 F 0.16

Shi-liang LI (李世亮),Dao-xin YAO (姚道新),Yi-ming QIU (邱义铭),Hye Jung KANG,E. W. CARLSON,Jiang-ping HU (胡江平),Gen-fu CHEN (陈根富),Nan-lin WANG (王楠林),Peng-cheng DAI (戴鹏程),

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Abstract

We use inelastic neutron scattering to study the low-energy spin excitations of polycrystalline samples of nonsuperconducting CeFeAsO and superconducting CeFeAsO_0.84F_0.16. Two sharp dispersionless modes are found at 0.85 and 1.16 meV in CeFeAsO below the Ce antiferromagnetic (AF) ordering temperature of "Graphic"

. On warming to above "Graphic"

, these two modes become one broad dispersionless mode that disappears just above the Fe ordering temperature "Graphic"

. For superconducting CeFeAsO_0.84F_0.16, where Fe static AF order is suppressed, we find a weakly dispersive mode center at 0.4 meV that may arise from short-range Ce–Ce exchange interactions. Using a Heisenberg model, we simulate powder-averaged Ce spin wave excitations. Our results show that we need both Ce spin wave and crystal electric field excitations to account for the whole spectra of low-energy spin excitations.

Keywords

iron pnictides / rare earth spin waves / crystal field

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Shi-liang LI (李世亮), Dao-xin YAO (姚道新), Yi-ming QIU (邱义铭), Hye Jung KANG, E. W. CARLSON, Jiang-ping HU (胡江平), Gen-fu CHEN (陈根富), Nan-lin WANG (王楠林), Peng-cheng DAI (戴鹏程),. Low-energy Ce spin excitations in CeFeAsO and CeFeAsO 0.84 F 0.16. Front. Phys., 2010, 5(2): 161‒165 https://doi.org/10.1007/s11467-009-0077-8