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Low-energy quasi-one-dimensional spin dynamics in charge-ordered La2-xSrxNiO4

PHYSICAL REVIEW B 83:9 (2011) ARTN 094414

Authors:

PG Freeman, D Prabhakaran, K Nakajima, A Stunault, M Enderle, C Niedermayer, CD Frost, K Yamada, AT Boothroyd
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Reversible pressure-induced amorphization of a zeolitic imidazolate framework (ZIF-4)

Chem Commun (Camb) 47 (2011) 7983-7985

Authors:

TD Bennett, P Simoncic, SA Moggach, F Gozzo, P Macchi, DA Keen, JC Tan, AK Cheetham

Abstract:

We report the reversible pressure-induced amorphization of a zeolitic imidazolate framework (ZIF-4, [Zn(Im)(2)]). This occurs irrespective of pore occupancy and takes place via a novel high pressure phase (ZIF-4-I) when solvent molecules are present in the pores. A significant reduction in bulk modulus upon framework evacuation is also observed for both ZIF-4 and ZIF-4-I.
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Spin anisotropy of the resonance peak in superconducting FeSe0.5Te0.5

PHYSICAL REVIEW B 83:18 (2011) ARTN 180506

Authors:

P Babkevich, B Roessli, SN Gvasaliya, L-P Regnault, PG Freeman, E Pomjakushina, K Conder, AT Boothroyd
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Probing photo-induced melting of antiferromagnetic order in La0.5Sr1.5MnO4 by ultrafast resonant soft X-ray diffraction

ArXiv 1012.496 (2010)

Authors:

H Ehrke, RI Tobey, S Wall, SA Cavill, M Först, V Khanna, Th Garl, N Stojanovic, D Prabhakaran, AT Boothroyd, M Gensch, A Mirone, P Reutler, A Revcolevschi, SS Dhesi, A Cavalleri

Abstract:

Photo-excitation in complex oxides1 transfers charge across semicovalent bonds, drastically perturbing spin and orbital orders2. Light may then be used in compounds like magnetoresistive manganites to control magnetism on nanometre lengthscales and ultrafast timescales. Here, we show how ultrafast resonant soft x-ray diffraction can separately probe the photo-induced dynamics of spin and orbital orders in La0.5Sr1.5MnO4. Ultrafast melting of CE antiferromagnetic spin order is evidenced by the disappearance of a (1/4,1/4,1/2) diffraction peak. On the other hand the (1/4,1/4,0) peak, reflecting orbital order, is only partially reduced. Cluster calculations aid our interpretation by considering different magnetically ordered states accessible after photo-excitation. Nonthermal coupling between light and magnetism emerges as a primary aspect of photo-induced phase transitions in manganites.
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Ultrafast resonant soft X-ray scattering in manganites: Direct measurement of time-dependent orbital order

Optics InfoBase Conference Papers (2010)

Authors:

H Ehrke, RI Tobey, S Wall, SA Cavill, D Prabhakaran, AT Boothroyd, M Gensch, P Reutler, A Revcolevschi, SS Dhesi, A Cavalleri

Abstract:

We present ultrafast resonant soft-x-ray diffraction measurements of time-dependent orbital order in the single-layer-manganite La0.5Sr1.5MnO4. These experiments reveal the appearance of a metastable phase with reduced ordering, different from any thermal state of the system. © OSA / UP 2010.