title: Fine-tuning the local symmetry to attain record blocking temperature and magnetic remanence in a single-ion magnet.
abstract: Remanence and coercivity are the basic characteristics of permanent magnets. They are also tightly correlated with the existence of long relaxation times of magnetization in a number of molecular complexes, called accordingly single-molecule magnets (SMMs). Up to now, hysteresis loops with large coercive fields have only been observed in polynuclear metal complexes and metal-radical SMMs. On the contrary, mononuclear complexes, called single-ion magnets (SIM), have shown hysteresis loops of butterfly/phonon bottleneck type, with negligible coercivity, and therefore with much shorter relaxation times of magnetization. A mononuclear Er(III) complex is presented with hysteresis loops having large coercive fields, achieving 7000 Oe at T=1.8 K and field variation as slow as 1 h for the entire cycle. The coercivity persists up to about 5 K, while the hysteresis loops persist to 12 K. Our finding shows that SIMs can be as efficient as polynuclear SMMs, thus opening new perspectives for their applications.
authors.affiliation: Theory of Nanomaterials Group and INPAC-Institute of Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijenlaan 200F, 3001 Leuven (Belgium).
authors.forename: Liviu
authors.initials: L
authors.lastname: Ungur
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Le Roy
authors.forename: Ilia
authors.initials: I
authors.lastname: Korobkov
authors.forename: Muralee
authors.initials: M
authors.lastname: Murugesu
authors.forename: Liviu F
authors.initials: LF
authors.lastname: Chibotaru
keywords: lanthanides; magnetic hysteresis; magnetic remanence; quantum chemistry; single-molecule magnets