1. PROPOSAL TO THE ISOLDE COMMITTEE – INTC/P258-Addendum 1 Study of Local Correlations of Magnetic and Multiferroic Compounds Aveiro 1, L’ Aquila 2, Lisboa 3, Moscow 4, Orsay 5, Porto 6, Sacavém 7, Stuttgart 8, Tokyo 9, Tsukuba 10, Vila Real 11 and the ISOLDE/CERN 12 Spokesman: V. S. Amaral Contact person: K. Johnston E. Alves 7, J.S. Amaral 1, V.S. Amaral 1, L.M. Amorim 7, J.P. Araújo 6, N.A. Babushkina 4, M. Baptista 7,6, J.G. Correia 7,12, A. Fenta 1, J.N. Gonçalves 1, H. Haas 7, H.-U. Habermeier 8, K. Johnston 12, A. L. Kholkin 1, A.M.L. Lopes 3, A.A. Lourenço 1, T.M. Mendonça 6, 12, G. Oliveira 3,6, S. Picozzi 2, M.R. Silva 3, J.B. Sousa 6, A. Stroppa 2, R. Suryanarayanan 5, P.B. Tavares 11, Y. Tokura 9, Y. Tomioka 10, J.M. Vieira 1

2. Ground State of these systems and interactions challenges the scientific community understanding Strong correlated electron systems: Subtle entanglement of spin, charge, orbital and lattice degrees of freedom Give rise to phenomena like HTC Superconductivity Colossal magnetoresistance Charge Ordered/Orbital Ordered Complex multi-scale world with: Intrinsic Inhomogeneities Clusters or stripes Phase segregation Multiferroic behaviour Local Correlations of Magnetic and Multiferroic Compounds

3. Gigantic response upon external stimulation Ability to couple multiple orders Competing Orders Ferromagnetic/Ferroelectric/Ferroelastic/ Charge/Orbital Additional degree of freedom in materials design leading to Potential applications for multifunction device Local Correlations of Magnetic and Multiferroic Compounds

4. Subjects to be Studied 1.Local environment in multiferroic compounds 2. Local distortions, polaron correlations and dynamics, magnetostructural effects near magnetic phase transitions Local Correlations of Magnetic and Multiferroic Compounds

5. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds In most of the cases the microscopic origin of magneto-electric coupling still left unclear and... other open questions remain... Is there a critical dimension below which the ferroelectricity or the magnetoelectric coupling will disappear or change in nature? Is there a way to elucidate a local effect? Picozzi & Ederer, 2009

6. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds An extensive study of the hyperfine interactions in a series of hexagonal and orthorhombic rare-earth manganites (RMnO 3, R= Nd, Sm, Eu, Gd, Tb, Ho, Y, Er, Lu) was performed in IS487 Tania Mendonça PhD Thesis (2012) Non centro-symmetric P63cm space group in the hexagonal crystalline structure at RT. A structural transition to the centro- symmetric P63/mmc space group occurs at ~1310K. Paraelectric to the ferroelectric phase transition at lower temperatures, TFE~833K. coexistence of two distinct local environments in all temperature range. High temperature crystalline structure allows only one nonequivalent rare-earth site. Minor EFG2 might be due to a distortion of the Er 4a site, whose contribution to the ferroelectric ordering of this compound shall be investigated EFG in ErMnO3

7. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds Cr 3+ ions dynamic off-centering in CdCr 2 S 4 spinel leading to magneto-electric clusters (T>Tc,~85K)  -  PAC technique using the 111 In  111 Cd probe Coexistence of two local environments. Cd probes at Cd (30 %) and Cr (70 %). Nat Mat ( submitted) Dynamic attenuation

8. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds Cr 3+ ions dynamic off-centering in CdCr 2 S 4 spinel leading to magneto-electric clusters using the 117 Cd  117 In probe ( 117 Cd probe replaces only the Cd position) With cubic environment EFG=0 Nat Mat ( submitted)

9. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds Cr 3+ ions dynamic off-centering in CdCr 2 S 4 spinel leading to magneto-electric clusters Presence of a dynamic state on simultaneously polar and magnetic clusters, arising from the atomic off-center displacement of Cr 3+ ions above Tc Cr 3+ ion role on the onset of local polar distortions, activated by thermal mechanism. Atomic displacement mechanism drives the relaxor behavior in the PM regime Pair Distribution Fn:Cr off centering Nat Mat ( submitted)

10. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds Relation between the electric polarization (P) and the electric field gradient (EFG) in ferroelectrics and multiferroics AND hyperfine HMF: local quantitative “description” of MF Vzz at the A site as a function of P 2 Coefficients of quadratic term of Vzz(P), at the A site, for a series of materials with the perovskite structure, as a function of atomic number Z A. How can we relate EFG and Electric polarization ? An ab-initio study calculating both in ABO 3 (changing deformation)

11. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds Relation between the electric polarization (P) and the electric field gradient (EFG) in ferroelectrics and multiferroics AND hyperfine HMF: local quantitative “description” of MF In YMn 2 O 5 Mn 4+ ions occupy the center of oxygen octahedra and Mn 3+ ions at pyramid dimers the FE polarization results purely from the spindependent Mn2-O-Mn1 hybridization and is due entirely to a redistribution of valence charge.

12. 1. Local environment in multiferroic compounds Local Correlations of Magnetic and Multiferroic Compounds Relation between the electric polarization (P) and the electric field gradient (EFG) in ferroelectrics and multiferroics AND hyperfine HMF: local quantitative “description” of MF When polarization appears without distortion: EFG and Electric polarization/Magnetic HF are related? ab-initio study in AB 2 O 5 (changing magnetic state drives polarization)

13. a) Charge-order induced or magnetically driven MF in RMnO 3 (R= trivalent lanthanides) manganites, RNiO 3 nickelates, MCrO 2 (M=Cu, Ag) chromites and chromium spinels DCr 2 O 4, (D=Mg, Cd, Zn, Hg). New case studies of: RMn 2 O 5 (R=Y,Lu) mixed valence manganites and DMnO 3 divalent (D=Ca/Ba/Sr) perovskite manganites b) MF where magnetism and ferroelectricity (FE) have distinct origins: RMnO 3 (R=Y,Lu) lattice distortion provides the coupling to the spin system through magnetostriction,BiFeO 3 ferrite and variants, where FE is due to Bi lone pairs. c) F irst-principle validation of relation between the electric polarization (P) and the electric field gradient (EFG), direct local probe of polarization. Ionic displacement and electronic contributions to EFG/P in Sr/Ba/CaMnO 3 Local Correlations of Magnetic and Multiferroic Compounds PAC studies: 111m Cd (49 m)  111 Cd 117 Cd(2.4h)  117 In and 111 Ag(7.45d)  111 Cd 199m Hg  199 Hg, 77 Se  77 Br and 48 Cr  48 V 1. Local environment in multiferroic compounds

14. Subjects to be Studied 1.Local environment in multiferroic compounds 2. Local distortions, polaron correlations and dynamics, magnetostructural effects near magnetic phase transitions Local Correlations of Magnetic and Multiferroic Compounds

15. 15 T C,i = 42.3-43.5 C T C,d = 30-32.6 C ΔT hysteresis = 9.7-13.5 C Red: heating Blue: cooling White: mix run (h&c) At a given T, the hyperfine field is the same, irrespective of cooling or heating the sample. MnAs Phases Low temperature Hexagonal structure (NiAs-type) ‏ Ferromagnetic metal Orthorhombic structure (MnP-type), Paramagnetic

16. 2. Local distortions, polaron correlations and magnetostructural effects a) an extension of a previous study in ferromagnetic insulator samples to ferromagnetic metallic (in the paramagnetic state) and to less distorted perovskites (rhombohedral). Systems to be studied include: 18 O/ 16 O isotopically modified Sm 1-x Sr x MnO 3 and doped SrTiO 3 samples. b) magneto-structural changes in first-order magnetic phase transition in Mn pnictides, Ni 2 MnGa and related systems. c) New case study of magnetic frustration reduction by local deformations in spin-ice systems, such as DCr 2 O 4, (D=Mg, Cd, Zn, Hg) at low temperatures (<20K). Local Correlations of Magnetic and Multiferroic Compounds PAC studies: 111m Cd (49 m)  111 Cd 117 Cd(2.4h)  117 In and 111 Ag(7.45d)  111 Cd 77 Se  77 Br

17. Experimental Facilities:Sample production and characterisation X-ray powder and single crystal diffraction: Aveiro, Porto Scanning Electron Microsc. (SEM) with EDX: Aveiro,Porto, Vila Real Transmission Electron Microscopy (HRTEM): Aveiro, Stuttgart Rutherford Backscattering/Channeling : Lisboa/Sacavém. Magnetic and Electrical properties: Aveiro, Orsay, Porto, Stuttgart, Tokyo/Tsukuba and CERN/ISOLDE Laboratory Family of samples Type of samples Aveiro/Porto/ Vila Real MoscowOrsayStuttgartTokyo and Tsukuba RMnO 3 + RMn 2 O 5 + (Ca/Ba/Sr)MnO 33 PelletsSolid State Reaction - BiFeO 3 PelletsSolid State Reaction La 1-x (Ca/Sr) x MnO 3 PelletsSolid State Reaction La/Pr 1-x (Ca/Sr) x MnO 3 S. Crystals Czochralski Czochralski aboveThin filmssputtering Pulsed Laser Ablation DCr 2 X 4 PelletsSolid State Reaction Sm 1-x Sr x MnO 3 16 O and 18 O Pellets Solid State Reaction RNiO 3 PelletsSolid State Reaction Mn pnictides +Ni 2 MnGa Pelletsarc melting

18.  Both the  -  and e - -  PAC techniques are well established at ISOLDE   -  PAC spectrometer 4K up to 1100 K under gas flow.  e - -  PAC spectrometer 25K up to 873 K under vacuum. Nuclear techniques with radioactive isotopes: Perturbed Angular Correlations- PAC Table II: Radioactive isotopes and techniques isotopeannealing  -  PAC  -  PAC 111m Cd (49 m)  111 Cd 199m Hg (42 m)  199 Hg 117 Ag (73 s)implant & wait for decay  117 Cd (2.4 h)  117 In (1.9 h) 111 Ag (7.45 d)  111 Cd 77 Br (57 h)  77 Se 73 Se (7.2 h)  73 As 48 Cr(21.6 h)  48 V

19. Beam time request 13 + (1-test) shifts REQUIRED ISOTOPE ISOLDE BEAM INTENSIT Y [AT/  C] TARGET ION SOURCE NUMBER OF SHIFTS 111m Cd ~ 5.0E8 Molten Sn plasma8 199m Hg ~ 2.0E8 Molten Pb plasma2 117 Cd (g.s.) 117 Ag (*)~ 5.0E8UC 2 laser (Ag) 2 111 Ag ~ 1.0E8 77 Br > 1.0E8ZrO 2 plasma 1 73 Se > 1.0E8 48 Cr ~ 1.3E5(**)ZrO 2 plasma 1-test total:13+1-test

20. Results from IS487 PhD/MSc thesis associated to work performed in IS487 (4+3) João Amaral: PhD in 2005-2009: Continued Pos-Doc 2010-2016 Tânia Mendonça: PhD in 2006-2012: Working at Isolde (Target Group) João Gonçalves: PhD in 2008-2011: Continued Pos-Doc 2012-2018 Célia Sousa: PhD 2008-2011: Continued Pos-Doc 2012-2018 Gonçalo Oliveira: MSc in 2009, PhD starting 2012 Marcelo Baptista Barbosa: MSc in 2010, PhD started 2011 João Horta Belo, MSc in 2010, PhD started 2011 Abel Fenta, MSc in 2011, PhD starting 2012

21. Results from IS487 Manuscripts in International Journals (5+2 submitted+3 in final preparation) First principles calculations of hyperfine parameters on the Ca manganite with substitutional Cd -modeling of a PAC experiment J. N. Gonçalves, H. Haas, A. M. L. Lopes, V. S. Amaral, J. G. Correia. Journal of Magnetism and Magnetic Materials,322, 1170-1173 (2010) Perturbed Angular Correlations Investigations on YMnO 3 Multiferroic Manganite T.M. Mendonça, A.M.L. Lopes, J.N. Gonçalves, J.G. Correia, P.B. Tavares, V.S. Amaral, C. Darie, J.P. Araújo Hyperfine Interactions 197,83 (2010) Magnetic hyperfine field at Cr site in AgCrO2 given by perturbed angular correlations G.N.P. Oliveira, A.M.L. Lopes, J.P. Araújo, T.M. Mendonça, J. Agostinho Moreira, A. Almeida, V.S. Amaral, J.G. Correia Hyperfine Interactions 197,123 (2010) Hyperfine Interactions in MnAs studied by Perturbed Angular Correlations of  -Rays using the probe 77 Br  77 Se and first principles calculations for MnAs and other Mn pnictides J. N. Gonçalves, V. S. Amaral, J. G. Correia, A. M. L. Lopes Physical Review B, 83, 104421 (2011) Local distortions in multiferroic AgCrO 2 Triangular Spin Lattice A.M.L. Lopes, G.N.P. Oliveira, T.M. Mendonça, J. Agostinho Moreira, A. Almeida, J.P. Araújo, V.S. Amaral, J.G. Correia Physical Review B, 84, 014434 (2011) Synthesis, Characterization and Local Probe Studies in Magnetoelectric AgCrO 2 G.N.P. Oliveira, A.M.L. Lopes, J.P. Araújo, T.M. Mendonça, J. Agostinho Moreira, A. Almeida, V.S. Amaral, J.G. Correia, Physica Status Solidi C (submitted) Cr 3+ ions dynamic off-centering in CdCr 2 S 4 leading to magneto-electric clusters Gonçalo Oliveira, André Pereira, Armandina M. L. Lopes, João Amaral, A. M. dos Santos, T.M. Mendonça, Celia Sousa, Yan Ren, Vitor Amaral, Guilherme Correia,, João Pedro Araújo Nat Mat ( submitted) Ferroelectricity and Electric Field Gradients: an ab-initio study J. N. Gonçalves, A. Stroppa, V. S. Amaral, J. G. Correia, T. Butz, and S. Picozzi Physical Review B (to be submitted) Hyperfine local probe study of alkaline-earth manganites BaMnO 3 and SrMnO 3 J. N. Gonçalves, V. S. Amaral, J. G. Correia, H. Haas, A. M. L. Lopes, J. P. Araújo, P.B. Tavares. Physical Review (to be submitted) Hyperfine parameters from first-principles in rare-earth multiferroic hexagonal manganites RMnO 3 (R = Y, Ho, Er, Lu). J. N. Gonçalves, V. S. Amaral, J. G. Correia Physical Review B (to be submitted) Oral Communications to International conferences(15 ;4 invited) Posters in International to International conferences Conferences (9)