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Dynamic pathway of the photoinduced phase transition of TbMnO 3

DOI: 10.1103/PhysRevB.96.184414 DOI Help

Authors: Elisabeth M. Bothschafter (Swiss Light Source) , Elsa Abreu (Institute for Quantum Electronics, ETH Zurich) , Laurenz Rettig (Swiss Light Source) , Teresa Kubacka (Institute for Quantum Electronics, ETH Zurich) , Sergii Parchenko (Swiss Light Source) , Michael Porer (Swiss Light Source) , Christian Dornes (Institute for Quantum Electronics, ETH Zurich) , Yoav William Windsor (Swiss Light Source) , Mahesh Ramakrishnan (Swiss Light Source) , Aurora Alberca (Swiss Light Source) , Sebastian Manz (ETH Zurich) , Jonathan Saari (Institute for Quantum Electronics, ETH Zurich) , Seyed M. Koohpayeh (Johns Hopkins University) , Manfred Fiebig (ETH Zurich) , Thomas Forrest (Diamond Light Source) , Philipp Werner (University of Fribourg) , Sarnjeet S. Dhesi (Diamond Light Source) , Steven L. Johnson (Institute for Quantum Electronics, ETH Zurich) , Urs Staub (Swiss Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 96

State: Published (Approved)
Published: November 2017
Diamond Proposal Number(s): 13355 , 13926

Abstract: We investigate the demagnetization dynamics of the cycloidal and sinusoidal phases of multiferroic TbMnO3 by means of time-resolved resonant soft x-ray diffraction following excitation by an optical pump. The use of orthogonal linear x-ray polarizations provides information on the contribution from the different magnetic moment directions, which can be interpreted as signatures from multiferroic cycloidal spin order and sinusoidal spin order. Tracking these signatures in the time domain enables us to identify the transient magnetic phase created by intense photoexcitation of the electrons and subsequent heating of the spin system on a picosecond time scale. The transient phase is shown to exhibit mostly spin density wave character, as in the adiabatic case, while nevertheless retaining the wave vector of the cycloidal long-range order. Two different pump photon energies, 1.55 and 3.1 eV, lead to population of the conduction band predominantly via intersite d−d or intrasite p−d transitions, respectively. We find that the nature of the optical excitation does not play an important role in determining the dynamics of magnetic order melting. Further, we observe that the orbital reconstruction, which is induced by the spin ordering, disappears on a time scale comparable to that of the cycloidal order, attesting to a direct coupling between magnetic order and orbital reconstruction. Our observations are discussed in the context of recent theoretical models of demagnetization dynamics in strongly correlated systems, revealing the potential of this type of measurement as a benchmark for such theoretical studies.

Journal Keywords: Magnetic phase transitions; Ultrafast phenomena; Multiferroics; X-ray diffraction

Subject Areas: Materials, Physics

Instruments: I06-Nanoscience

Other Facilities: Swiss Light Source