88276 20200716101503.0 doi 10.1039/c8dt05044a sideral 111507 ART-2019-111507 eng Bartolomé, E. Slow relaxation in a {Tb 2 Ba(a-fur) 8 } :N polymer with Ln = Tb(iii) non-Kramers ions 2019 Access copy available to the general public Unrestricted We report the synthesis, crystal structure and magnetic properties of a new heteronuclear polymeric complex based on non-Kramers Tb ions and carboxylic a-fur = C 4 H 3 OCOO ligands: {[Tb 2 Ba(a-fur) 8 (H 2 O) 4 ]·2H 2 O} n . The a-furoate ligands consolidate 1D zig-zag chains running along the c-axis, formed by Tb 2 dimers separated by Ba ions. Ab initio calculations, in combination with the fit of experimental data, predict that the single-ion magnetic ground state is highly anisotropic and consists of a quasi-doublet with a ¿ Tb /k B = 3.22 K gap, well separated from the next excited state, while the gap for the Tb 2 dimer is ¿ 2Tb /k B = 2.58 K. Static magnetization and heat capacity measurements show that, magnetically, the system can be modeled as dimers of non-Kramers Tb ions, coupled by an antiferromagnetic intradimer interaction J'*/k B = -1.6 K. Dipolar interactions couple the Tb ions in the dimer with their first neighbour ions along the chain, with J''*/k B = -0.15 K, and with the surrounding ions out of the chain, with maximum J'''*/k B = -0.03 K. Ac susceptibility measurements in H = 0 performed down to 50 mK temperatures have enabled us to observe slow relaxation of magnetization, with an Orbach-like activation energy of U/k B = 1.1 K. It is assigned to the sluggish response of the 3D spin system due to a short-range ordering, possibly enhanced by the presence of disorder caused by defects in the polymeric chains. Under the application of a magnetic field, the system slowly relaxes by two distinct direct processes, strongly affected by a phonon bottleneck effect. We discuss the different relaxational phenomenology of the new complex in comparison with that of the isostructural {[Dy 2 Ba(a-fur) 8 (H 2 O) 4 ]·2H 2 O} n , differing only in the Kramers nature of the ions, and the mononuclear {Ln(a-fur) 3 (H 2 O) 3 } n (Ln = Tb, Dy) complexes, previously reported. info:eu-repo/grantAgreement/ES/MINECO/MAT2014-53921-R info:eu-repo/grantAgreement/ES/MINECO/MAT2015-68200-C2-2-P info:eu-repo/grantAgreement/ES/MINECO/MAT2017-83468-R info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 4.174 2019 CHEMISTRY, INORGANIC & NUCLEAR 5 / 45 = 0.111 2019 Q1 T1 1.048 2019 Inorganic Chemistry 2019 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion (orcid)0000-0002-5999-341X Arauzo, A. Universidad de Zaragoza (orcid)0000-0002-9208-0807 Luzón, J. Melnic, S. Shova, S. Prodius, D. (orcid)0000-0002-0047-1772 Bartolomé, J. Universidad de Zaragoza Amann, A. Nallaiyan, M. Spagna, S. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 48, 15 (2019), 5022-5034 Dalton Trans. Dalton Transactions 1477-9226 1288515 http://zaguan.unizar.es/record/88276/files/texto_completo.pdf Postprint 111104 http://zaguan.unizar.es/record/88276/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:88276 articulos driver 2020-07-16-09:14:18 ARTICLE