From surfaces to magnetic properties: special section dedicated to Juan Rojo

Abstract

Surface physics and magnetism, in particular the connection between surface defects, reduced dimensionality or size, crystal structure, electronic density of states and the mechanical and magnetic properties of solids, were always at the core of Juan Rojo’s scientific interest and output. Both fields seem to meet at the nanoscale, a privileged playing field which is ideal for testing theoretical concepts, exploring new physics or probing a wealth of new, stunning and unheard-of applications. Upon reducing size or dimensionality, either in bulk systems or in thin films, surfaces and surface effects are telling. Thus, for instance, an ultra-thin coating can make nanoparticles of non-magnetic materials exhibit magnetic behaviour; or atomic steps can modify the local mechanical properties of a metallic single crystal.In this special section there are eight invited papers by disciples and close collaborators of Juan Rojo, that cover an ample spectrum of the above mentioned topics. The first paper, by Palacio et al, investigates the temperature and oxygen partial pressure conditions for FeO mono- and bi-layer growth on Ru(0001). The following paper, by Cortés-Gil et al, reports on the dramatic change in the electric resistivity of the manganite perovskite (La0.5Ca0.5)z MnO3 as a function of Ca content, an effect related to the removal of a charge-ordered state and a magnetic transition. Baeza et al study biomaterials for bone cancer treatment and skeletal reinforcing, as well as targeted magnetic nanoparticles used for intracell hyperthermia in cancer therapies. In the following paper, Marcano et al, assisted by a multi-technique approach, revisit the extraordinarily rich magnetic phase diagram of the Kondo system CeNi1−x Cux down to 100 mK temperatures. The magnetic field dependence of the martensitic transition temperature of the meta-magnetic shape memory alloy Ni50Mn34.5In15.5 in a crystalline and amorphous phase, in fields up to 13 T, is the subject of the paper by Barandiarán et al. In the following paper, Crespo et al review the effect of organic and inorganic coatings on magnetic nanoparticles, showing that the coating can tune the magnetic properties of metallic and oxide nano-sized particles. Barja et al report on ordered magnetic ion structures formed by evaporation of Mn and Fe on self-assembled layers of tetracyanoquinodimethane (TCNQ) molecules on Cu(111). Finally, Rodríguez de la Fuente et al investigate the role of surface defects on the physico-chemical properties of metals and oxides in a variety of scenarios, showing how the surface controls the mechanical properties probed at the nanoscale or the chemical reactivity.AcknowledgmentsThe editors are grateful to all the invited contributors to this special section of Journal of Physics: Condensed Matter . We also thank the staff of IOP Publishing for handling the administrative matters and the refereeing process, and for their patience and helpful disposition.From surfaces to magnetic properties contentsFrom surfaces to magnetic properties: special section dedicated to Juan Rojo A Mascaraque, O Rodríguez de la Fuente and Miguel A González-BarrioJuan Rojo: the surface science and science politics maker in Spain A Mascaraque, O Rodríguez de la Fuente, Miguel A González-Barrio, Javier Solana, Luis Oro and Ana CrespoInitial stages of FeO growth on Ru(0001) I Palacio, M Monti, J F Marco, K F McCarty and J de la FigueraSurprising resistivity decrease in manganites with constant electronic density R Cortés-Gil, M L Ruiz-González, J M Alonso, J L Martínez, A Hernando, M Vallet-Regí, and J M González-CalbetThermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles A Baeza, D Arcos and M Vallet-RegíRevisited magnetic phase diagram for CeNi1-xCux system: spin-glass in the weak interaction limit N Marcano, J I Espeso and J C Gómez SalMagnetic field and atomic order effect on the martensitic transformation of a metamagnetic alloy J M Barandiaran, V A Chernenko, E Cesari, D Salas, J Gutierrez and P LazpitaMagnetism in nanoparticles: tuning properties with coatings Patricia Crespo, Patricia de la Presa, Pilar Marín, Marta Multigner, José María Alonso, Guillermo Rivero, Félix Yndurain, José María González-Calbet and Antonio HernandoOrdered arrays of metal–organic magnets at surfaces Sara Barja, Daniel Stradi, Bogdana Borca, Manuela Garnica, Cristina Díaz, Josefa M Rodriguez-García, Manuel Alcamí, Amadeo L Vázquez de Parga, Fernando Martín and Rodolfo MirandaSurface defects and their influence on surface properties O Rodríguez de la Fuente, M A González-Barrio, V Navarro, B M Pabón, I Palacio and A Mascaraque