1 / 21

C. Doubrovsky 1 , F. Bouquet 1 , C. Pasquier 1 , P. Senzier 1

STUDY OF THE INTERPLAY BETWEEN SPIN, CHARGE AND LATTICE IN MULTIFERROIC OXIDES RMn2O5 (R= Nd , Pr). C. Doubrovsky 1 , F. Bouquet 1 , C. Pasquier 1 , P. Senzier 1 M. Greenblatt 3 , S. Petit 2 , G. Andre 2 , F. Damay 2 , P. Foury 1. phD director, Pascale Foury.

ata
Télécharger la présentation

C. Doubrovsky 1 , F. Bouquet 1 , C. Pasquier 1 , P. Senzier 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. STUDY OF THE INTERPLAY BETWEEN SPIN, CHARGE AND LATTICE IN MULTIFERROIC OXIDES RMn2O5 (R= Nd, Pr) C. Doubrovsky1, F. Bouquet1, C. Pasquier1, P. Senzier1 M. Greenblatt3, S. Petit2,G. Andre2, F. Damay2, P. Foury1 phD director, Pascale Foury 1Laboratoire de Physique des Solides (LPS), Orsay, France 2Labortaoire Léon Brillouin (CEA-CNRS), CEA Saclay, France 3Wright – RiemanLaboratories, RutgersUniversity, New Jersey

  2. I. 1 Multiferroics Spintronic Type I : Weaklycoupledorders(BiFeO3) 4 states memory Type II : Strongcouplingbetweenordersleading to ferroelectricity (RMn2O5) Electricalwriting/Magneticreading Issue : Microscopicorigin of the magneto-electriccouplingDzyaloshinskiiMoriya or Exchange interaction

  3. I. 2 Origin of the magneto-electriccoupling Magnetostriction effect Non colinear : Dzyaloshinskii-Moriya interaction O2- ligands shifts Colinear : Exchange interaction Mn3+ ions shifts P R3+ Mn4+ Mn3+ S-W Cheong et al. Nature (2007)

  4. J couplings in RMn2O5 Magnetic superexchange interactions Ji = 3,5 are shown by double sided arrows. P G Radaelli et al. J. P Condens. Matter (2008) • (ab) plane– Loops of 5 Mn spins – • J3Mn3+/Mn4+ J4Mn3+/Mn4+ through O2- J5Mn3+/Mn3+ • Along c – Mn4+ chains – • J1throughR3+ J2 through Mn3+

  5. I. 3 Rare earth influence in RMn2O5  Gal case R = Y, Tb, Ho, Er, Tm  3 to 4 transitions (<50K) TbMn2O5 Noda et al. J. P. Condens. Matter(2008) non magnetic R R= Bi (½ 0 ½) CP - ferroelectric R=La (00 ½) CP - not ferroelectric Lighter Rare Earth ?

  6. Syntheses, RutgersUniversity II.1 ThermodynamicProperties Specificheat on a PrMn2O5 powder LPS, PPMS Quantum design. Transitions at 20K and 25K

  7. II.2 MagneticProperties 132K Curie Law: θc = 132K C ~1.46 10-2emu.K.g-1.Oe-1 3,5 µB (<µeff>= <µMn4+ + µMn3+ + µPr3+ > = 4,1 µB ) 25K TC TN1 Susceptibility of a PrMn2O5 powder (SQUID, RowanUniversity, NJ) 25K transition AFM 20K transition not visible (smallrearangement of the magnetic moment)

  8. II.3 DielectricProperties Cp (pF) T(K) Dielectric constant of PrMn2O5 and TbMn2O5 powders(LPS, Orsay) No ferroelectric transition 20K effect ? electromagnon as suggested in TbMn2O5?

  9. III.1Nuclear structure of PrMn2O5 Powder X-ray diffraction pattern takenat 10 and 70K of a polycristallinesample Cristal beam line (SOLEIL) CentrosymmetricPbam structure confirmed No structural variation (> 10-3) between 50 & 10K  No significantmagneto-strictioneffect

  10. III.2Magnetic structure of PrMn2O5 λ= 2,4226 A Magneticspectra of PrMn2O5 powder, recorderd by elastic neutron diffraction (G4.1, Orphée LLB) IntegratedIntensity of the 2 sets of satelitespeaks • 2nd - ordercommensuratemagnetic transitions at : • 25K : q1 (1/2 00) • 20K : q2 (001/2) Origin : Another PrMn2O5 phase?

  11. III.2Magnetic structure of PrMn2O5 TbMn2O5 PrMn2O5 Mn3+ Mn4+ P Pr3+ O2- b a 25K - q1 (1/2 00) q(1/2 01/4) G. R. Blake, Physical Review B (2005) • Similar to TbMn2O5 and other RMn2O5 • All magneticatomsplay part in the magnetic structure

  12. Perspectives • Mesure and Modelisation of spinwaves J coupling values in PrMn2O5 & TbMn2O5 (Inelastic neutron diffraction) • Understanding the low –T transition TbMn2O5

  13. Thankyou for your attention

  14. Interplay between spin, charge and lattice in multiferroics RMn2O5 I.Magnetoelectriccoupling • Multiferroics • Origin of the magnetoelectriccoupling • Rare earthinfluency in RMn2O5 II.PrMn2O5caracterisation • Synthesis of RMn2O5 • Properties of PrMn2O5 III. Nuclear and magnetic structures of PrMn2O5 2/9

  15. In the ‘proper’ ferroelectrics, structural instability towards the polar state, associated with the electronic pairing, is the main driving force of the transition. • On the other hand, if polarization is only a part of a more complex lattice distortion or if it appears as an accidental by-product of some other ordering, the ferroelectricity is called ‘improper’

  16. Solid State Chemistry Pr6O11 + 12Mn 6 PrMn2O5 Mn (metal basis) washed in dilute HCl, dissolved in HNO3 XR- Results 600°C 1100°C O2 Ref. : H. Satoh, S. Suzuki, K. Yamamoto, N Kamegashira, Phase Stabilities of LnMn2O5 (Ln = rare earth), Alloys and Compounds (1995) 6/12

  17. Susceptibility a//H b//H c//H 0 10 20 30 40 50 PrMn2O5Electrolysis 1 mm

  18. TbMn2O5 CM magnetic structure Plan (ab) Along c direction Mn3+ Mn3+ Mn4+ Mn4+ b O2- Tb3+ a Colinear moments on a same site, with quite strange directions. Tb moment shave zero value when it is between AF ordered Mn layers. q(1/2 01/4)

  19. Other magnetic Structure of RMn2O5 TbMn2O5 Magnetic frustration along b b Loops of 5 spins : AFM order cannot be estblished a AFM along a

  20. Reversible flipping of electric polarization in TbMn2O5

More Related