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Seminars & Lectures

* TITLE

Magnetic Excitations in Multi-Orbital Models for Iron Pnictides

* SPEAKERS

Name	Affiliation	E-mail
Nimisha Raghuvanshi	APCTP	Nimisha.raghuvanshi(at)apctp.org

* HOST(Applicant)

Name	Affiliation	E-mail
Alireza Akbari	APCTP	alireza(at)apctp.org

* DATE / TIME

2017-07-28, am 10:00 ~

* ABSTRACT

Study of magnetic excitations provides detailed understanding of effective magnetic interactions in correlated electron systems. Spin wave excitations in iron pnictides have been intensively investigated since the discovery of magnetism in these iron based superconductors. Inelastic neutron scattering and angle resolved photoemission spectroscopy experiments have revealed various features of this (pi, 0, pi) ordered antiferromagnet. These observations have highlighted the limitations of various existing theoretical models and approaches. In this talk, I will discuss calculation of magnetic excitations in different multi-orbital models for iron pnictides aimed at understanding the major characteristic features of magnetic excitation spectra within a single theoretical framework. We propose that the characteristic maximum spin wave energy at the ferromagnetic zone boundary is the result of strong ferromagnetic spin couplings generated due to the exchange of the (virtual) particle-hole pair. Conditions on the microscopic Hamiltonian parameters of the multi-orbital model, which favor the stabilization of the spin density wave state and correct sign of the orbital order within the constraints on the Fermi surface structure are identified. The role of nesting in the stabilization of the spin density wave ordered state is examined.

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