Magnetic ordering-induced multiferroic behavior in [CH 3 NH 3 ][Co(HCOO) 3 ] Metal-Organic Framework.

Transcription

1 Supporting Information Magnetic ordering-induced multiferroic behavior in [CH 3 NH 3 ][Co(HCOO 3 ] Metal-Organic Framework. L. Claudia Gómez-Aguirre a, Breogán Pato-Doldán a +, J. Mira b, Socorro Castro-García a, María Antonia Señarís-Rodríguez a, Manuel Sánchez-Andújar a, John Singleton c and Vivien S. Zapf c *. a Department of Fundamental Chemistry, Faculty of Sciences, University of A Coruña, Campus A Coruña, 1571 A Coruña, Spain. b Department of Applied Physics, University of Santiago de Compostela, 1578 Santiago de Compostela, Spain. c National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 8755, United States. * vzapf@lanl.gov S1

2 Synthesis CoCl H O (98%, Sigma-Aldrich, NaHCOO ( 99%, Sigma-Aldrich, CH 3 NH HCl ( 99%, Sigma-Aldrich and HCONHCH 3 (99%, Sigma-Aldrich were commercially available, reagent grade, and used as purchased without further purification. [NH 3 CH 3 ][Co(HCOO 3 ] was first prepared by M. Boca et al. 1 However, the reaction conditions such as the use of dry solvents and the month time necessary to obtain crystals led us to seek an alternative method. The synthetic method used here is an adaptation of the method previously described for analogous MOFs of formula [(CH 3 NH ][M(HCOO 3 ]. In a typical experiment three aqueous solutions of CoCl 6H O (3 ml,.33 M, CH 3 NH 3 Cl (3 ml,.33 M and NaHCOO ( ml 1.5 M were mixed to give a Co + / CH 3 NH + 3 /3 HCOO - stoichiometric solution. Afterwards, 8 ml of methylformamide (HCONHCH 3 were added. The resultant solution was heated in a Teflon lined autoclave (5 ml at 1 C for 7 hours. After the thermal treatment, pink crystals of Co-MOF were obtained (Fig. S1 with a yield of 3%. Slow evaporation of the mother liquid for days increased the yield of the reaction up to 85%. The obtained crystals are stable in air, mother liquid, methanol and ethanol. 1 mm Figure S1. Photograph of a Co-MOF crystal obtained by the here described solvothermal method. Sample Characterization Single-crystal data sets were collected at 1 K in a Bruker-Nonius x8 ApexII X-ray diffractometer equipped with a CCD detector and using monochromatic MoKα1 radiation (λ =.7173 Å. A suitable crystal of the sample was chosen and mounted on a glass fiber using instant glue. The crystal temperature was maintained using a cold stream of nitrogen from a Kyroflex cryostream cooler. The data integration and reduction was performed using the Apex V.1.-7 (BrukerNonius, 5 suite software. The intensity was corrected for Lorentz and polarization effects and for absorption by semiempirical methods on the basis of symmetry-equivalent data using SADABS ( of the suite software. The purity of the sample was studied by X-ray powder diffraction (XRPD at room temperature in a Siemens D-5 diffractometer using CuKα radiation (λ = Å. The XRPD pattern was analyzed by the Le Bail profile analysis using the Fullprof software. 3 Thermogravimetric analysis (TGA were carried out in a TGA-DTA Thermal Analysis SDT96 equipment coupled to a Bruker Vector IR spectrophotometer. For these experiments approximately 5 mg of the sample was heated at a rate of 5 K/min from 3 to 13 K using corundum crucibles under a flow of dry nitrogen. Physical measurements The magnetic characterization of this sample has been done under static (SQUID and VSM and pulsed magnetic fields. A powdered sample was measured in the SQUID while for VSM and pulsed fields a single crystal previously oriented by single-crystal X-ray diffraction, was used. The low field magnetic properties of the crystalline powder were studied in a Quantum Design Magnetic Properties Measurement System (MPMS Superconducting Quantum Interference Device (SQUID magnetometer up to 5 T. The magnetization of single crystals was measured in a Quantum Design Vibrating Sample Magnetometer (VSM in a 1 T Physical Properties Measurement System (PPMS at the NHMFL pulsed-field facility, up to 13 T. The experimental susceptibilities were corrected for the diamagnetism of the constituent atoms (using the Pascal's tables and an experimental correction for the sample holder was applied. S

3 The superconducting magnets contain remnant magnetic flux even at zero field, which is 1 Oe in the 5 T magnet and 1 Oe in 1 T magnet after sweeping down to zero from peak field. This field is reduced to 1 Oe in the 5 T magnet and 1 Oe in the 1 T magnet after a degaussing procedure, conducted before zero -field cooling. We have verified a 1-1 Oe remnant field after degaussing in our 1 T magnet using a Hall sensor. Pulsed-field magnetization experiments were done in a 1.5mm bore, 1.5mm long, 15-turn radially-compensated coil, constructed from 5 gauge high-purity copper wire. 5,6 The changing magnetic field induced a changing sample magnetic moment that in turn induced a voltage in the coil proportional to dm/dt. This signal was integrated to determine the magnetization M vs magnetic field H. 6 The samples were mounted within a 1.3mm diameter ampoule that can be moved in and out of the coil. 5 Accurate values of M were obtained by subtracting empty coil data from that measured under identical conditions with the sample present. Fields were provided by the 65 T capacitor-driven short-pulse magnet at the NHMFL pulsed field facility sited in Los Alamos 7 (LANL. The susceptometer was placed within a 3 He cryostat providing temperatures down to. K. The applied magnetic field was measured by integrating the voltage induced in a ten-turn coil calibrated by observing the de Haas van Alphen oscillations of the belly orbits of the copper coils of the susceptometer. 5 Data is shown on upsweep. There an open question for the H [11] and [1-1] directions as to whether the hysteretic phase transition can be observed on the downsweep near H =, as it is in superconducting magnets. Unfortunately the noise in the pulsed-field magnetization data diverges when approaching H = on the downsweep, because the magnetic field sweep rate exponentially approaches zero as well. For electric polarization measurements, the samples were coated on parallel faces with silver paint and leads were attached. The samples were verified to be insulating with no leakage currents possible on the scale of magnetoelectric current measurements observed here. The induced magnetoelectric current due to due to the changing surface charge was measured on one contact with a Stanford Research 57 current to voltage converter (which represents a virtual ground while the other contact was directly grounded. Measurements were performed during magnetic field pulses. The samples were cooled by immersion in liquid 3 He while millisecond magnetic pulses were applied. The results of 1 T pulses are shown here. The resulting magnetoelectric current I was integrated in time to extract the polarization change P. The data shown is taken on the upsweep of the magnet during which the sweep rate is more than 1x faster than during the downsweep and therefore providing greater induced current, allowing us to resolve the effect. No dependence was observed on poling electric fields up to 1 V applied during cooling before the measurements. The individual magnetic field pulses up to 1 Tesla and back to zero are separated by waiting times of the order of minutes. 8 The magnetic field sweep rates in pulsed magnetic fields are shown in Fig. S1. Phase diagrams in Fig. 6 of Co-MOF along [1] and [11] orientations were constructed as follows: data points were extracted from peaks in the 1 st derivative of both magnetization (Fig. S9 for [1] and Fig. S1 for [11] and electric polarization with magnetic field (Fig. 5. The transition to the paramagnetic PM phase was estimated from the saturation of the magnetization with field (peak in the nd derivative. S3

4 Intensity (a.u.,, 11 5 Observed Calculated Obs.-Calc. Bragg positions ( o Figure S. Le Bail refinement of the XRPD pattern of Co-MOF at room temperature showing good agreement between the experimental data and the proposed model for the fitting S

5 Intensity (a.u. Weight loss (% 1 8 [CH 3 NH 3 ][Co(HCOO 3 ] 33.8% (calc. 3.1% CH 3 NH + CO + H O 6 Co(HCOO.8% (calc. 38.1% CO + H O T (K CoO + Co Figure S3. Thermogravimetric curve of Co-MOF. Simulated CoO Experimental Simulated Co (deg. Figure S. XRPD pattern of the product obtained after heating Co-MOF at 873 K compared with the XRPD simulated for Co 9 and CoO. 1 S5

6 Table S1. Crystallographic data for Co-MOF Compound reference Methylammonium Cobalt (II Formate Chemical formula C H 9 CoNO 6 Formula Mass 6.5 Temperature 1 K Crystal system Orthorhombic a/å 8.99( b/å (6 c/å ( α/ 9. β/ 9. γ/ 9. Unit cell volume/å (7 Temperature/K 1( Space group Pnma No. of formula units per unit cell, Z Radiation type MoKα Absorption coefficient, μ/mm No. of reflections measured 7 No. of independent reflections 979 R int.539 Final R 1 values (I> σ(i.37 Final wr(f values (I> σ(i.977 Final R 1 values (all data.65 Final wr(f values (all data.137 Goodness of fit on F 1.18 S6

7 M( B M( B a..6 FC Polycrystals ZFC M ( B.. 1 Oe b T (K Single crystal [11] FC ZFC 5 Oe 5 Oe 1 Oe. c T (K Single crystal [1] FC ZFC Oe 5 Oe 75 Oe 1 Oe T (K Figure S5. Magnetization of Co-MOF measured at 5 Oe/s in a superconducting magnet, as a function of temperature T at different magnetic fields H, after zero field cooling (ZFC or field cooled (FC for a a polycrystalline sample ( ZFC ~1 Oe in a 5 T magnet and a single crystal ( ZFC ~1 Oe in a 1 T magnet along b [11] and c [1] orientations. The long-range magnetic ordering temperature, around 15.9 K, is indicated by a dashed line. S7

8 1 8 m -1 (mol/cm 3 6 m -1 = T/C - /C C= 3.5 cm 3 K/mol = -3.5 K T (K Figure S6. Temperature dependence of the inverse molar susceptibility χ m 1 of Co-MOF. The solid red line corresponds to a fit to the Curie Weiss law. Table S.. Comparison between magnetic data from some other formate frameworks with Co Co linkages through anti anti formate bridges, and formula [AmineH][Co(HCOO 3 ] and our [CH 3 NH 3 ][Co(HCOO 3 ] compound. a. b. c. [AmineH][Co(HCOO 3 ] [CH 3 NH 3 ] [(CH 3 NH ] ref. [C(NH 3 ] ref.11 T t / K C / cm 3 K mol a θ / K -3.5 a χ m T (3K / cm 3 K mol μ eff / μ B J / K -.9 b g.7 c.8.83 from fitting to the Curie-Weiss law (between and 3 K, R =.9997 from the molecular field theory of antiferromagnetism from the Curie constant value S8

9 M ( B M( B...5 K 5. K 1. K Magnetic field (T Figure S7. Isothermal magnetization M(T,H for Co-MOF along [1] at different temperatures, measured in a VSM in a 1 T PPMS at field sweep rate of 5 Oe/s K. K 6. K Magnetic Field (T Figure S8. Isothermal magnetization M(T,H for Co-MOF along [11] at different temperatures, measured in a VSM in a 1 T PPMS at field sweep rate of 5 Oe/s. S9

10 dm/dh Critical field (T M( B M( B K 1.8 K.5 K.5 K 3.13 K 3.55 K 3.97 K 5.97 K 7.96 K 9.97 K K K 1.96 K K Magnetic field (T Magnetic field (T Magnetic field (T.58K 1.8 K.5 K.5 K 3.13 K 3.55 K 3.96 K 5.97 K 7.96 K 9.97 K K K 1.96 K K Temperature (K Figure S9. Pulsed field magnetization of Co-MOF data for M and H along [1] at different temperatures, shown in 3D, D and as derivative for clarity. S1

11 1 8 6 Magnetic field (T 1.5 dm/dh (a.u. dm/dh (a.u..7 K M ( B M ( B 3..7 K 1.56 K 1.88 K.18 K. K 3. K 3.5 K 3.96 K 3.99 K 3.99 K.5 K 5. K 5.5 K 6. K 6.5K 6.99 K 7.5 K 8. K 8.5 K 1. K 17. K x1-5 3.x1-5.x1-5 1.x Magnetic field (T 6 Magnetic field (T K 1.56 K 1.88 K.18 K. K 3. K 3.5 K 3.96 K 3.99 K.5 K 5. K 5.5 K 6. K 6.5 K 6.99 K 7.5 K 8. K 8.5 K 1. K 17. K Magnetic field (T Critical field (T Temperature (K Figure S1. Pulsed field magnetization of Co-MOF data for M and H along [11], at different temperatures, shown in 3D, D and as a derivative for clarity. As shown in the figure, the kink appears split into several close peaks. S11

12 Figure S11. Pulsed field magnetization of Co-MOF data for M and H along [1-1] at different temperatures, shown in 3D and in D as a derivative for clarity. Figure S1. Pulsed magnetic field vs time t and sweep rate in 65 T capacitor-driven short pulse magnet. The sweep rate scales with the peak field of the pulse. S1

13 References (1 Boča, M.; Svoboda, I.; Renz, F.; Fuess, H. Acta Crystallogr. Sect. C, 6, m631 m633. ( Wang, X.-Y.; Gan, L.; Zhang, S.-W.; Gao, S. Inorg. Chem., 3, (3 Rodríguez-Carvajal, J. Comm. Powder Diffr. (IUCr. Newsl. 1, 6, ( Bain, G. A.; Berry, J. F. J. Chem. Educ. 8, 85, 53. (5 Goddard, P.; Singleton, J.; Lima Sharma, A.; Morosan, E.; Blundell, S.; Bud ko, S.; Canfield, P. Phys. Rev. B 7, 75, 96. (6 Detwiler, J.; Schmiedeshoff, G.; Harrison, N.; Lacerda, A.; Cooley, J.; Smith, J. Phys. Rev. B, 61,. (7 Jaime, M.; Lacerda, A.; Takano, Y.; Boebinger, G. S. J. Phys. Conf. Ser. 6, 51, (8 Zapf, V. S.; Kenzelmann, M.; Wolff-Fabris, F.; Balakirev, F.; Chen, Y. Phys. Rev. B 1, 8, 6. (9 Taylor, A.; Floyd, R. W. Acta Crystallogr. 195, 3, (1 Wyckoff, R. W. G. Crystal Structures; Interscience Publishers: New York, 1963; Vol. 1. (11 Hu, K.-L.; Kurmoo, M.; Wang, Z.; Gao, S. Chem. Eur. J. 9, 15, S13