Slow magnetic relaxation and hysteresis effects of dynamic origin have been observed above liquid helium temperature in a chain compound (see picture), comprising CoII centers organic radicals, without any evidence phase transition to three-dimensional order. These results are the first slow dynamics predicted for one-dimensional systems with Ising anisotropy, they open possibility storing information single nanowire.

Informationsspeicherung in einzelnen magnetischen Nanodrähten? Die Grundlage hierfür könnten erste Hinweise auf die langsame Dynamik liefern, welche für eindimensionale magnetische Systeme mit Ising-Anisotropie vorhergesagt wurde: Langsame Relaxation und Hystereseeffekte dynamischen Ursprungs wurden oberhalb der Temperatur flüssigen Heliums einer Kettenverbindung beobachtet (siehe Bild), aus CoII-Zentren organischen Radikalen aufgebaut ist, ohne dass es einen Phasenübergang zu...

The problem of finite-size effects in s=1/2 Ising systems showing slow dynamics the magnetization is investigated introducing diamagnetic impurities a Co2+-radical chain. static magnetic properties have been measured and analyzed considering peculiarities induced by ferrimagnetic character compound. dynamic susceptibility shows that an Arrhenius law observed with same energy barrier for pure doped compounds while prefactor decreases, as theoretically predicted. Multiple spin reversal has...

A comprehensive investigation of rotatable anisotropy in a Fe${}_{0.8}$Ga${}_{0.2}$ thin film with stripe domain structure has been performed comparing static and dynamic measurements. The stripes' formation their rotation under transverse magnetic field have imaged by force microscopy. ${H}_{\mathrm{rot}}$ was determined fitting the frequency evolution dipole-dominated magnetostatic spin-wave mode versus in-plane orientation domains, measured Brillouin light scattering absence any dc or ac...

We investigate theoretically and experimentally the static magnetic properties of single crystals molecular-based single-chain magnet formula ${[\text{Dy}{(\text{hfac})}_{3}\text{NIT}({\text{C}}_{6}{\text{H}}_{4}\text{OPh})]}_{\ensuremath{\infty}}$ comprising alternating ${\text{Dy}}^{3+}$ organic radicals. The molar susceptibility ${\ensuremath{\chi}}_{M}$ displays a strong angular variation for sample rotations around two directions perpendicular to chain axis. A peculiar inversion between...

The in-plane rotation of magnetic stripe domains in a 65-nm magnetostrictive ${\mathrm{Fe}}_{0.8}{\mathrm{Ga}}_{0.2}$ epitaxial film was investigated combining force microscopy, vibration sample magnetometry, and x-ray resonant scattering measurements. We analyzed the behavior pattern under application bias field along direction perpendicular to axis, made comparison with analogous at remanence. experimental results have been explained by means micromagnetic simulations, supported energy...

We determine the effective dipolar interaction between single domain two-dimensional ferromagnetic particles (islands or dots), taking into account their finite size. The first correction term decays as ${1/D}^{5},$ where D is distance particles. If are arranged in a regular array and magnetized plane, we show that reinforces antiferromagnetic character of ground state square lattice, one triangular lattice. also spin-wave spectrum evaluate how Curie temperature an ensemble magnetic scales...

We have imaged the stripe domain structure of perpendicularly magnetized fcc ultrathin Fe films grown on Cu(100). The phase has a strong local orientational order and sustains two kinds fluctuations predicted by Abanov et al. [Phys. Rev. B 51, 1023 (1995)]: meandering dislocations. Before reaching Curie temperature, stripes transform into new so far unobserved structure, characterized domains with predominantly square corners. argue that this is tetragonal liquid proposed to separate from...

The slow dynamics (10^-6 s - 10^4 s) of the magnetization in paramagnetic phase, predicted by Glauber for 1d Ising ferromagnets, has been observed with ac susceptibility and SQUID magnetometry measurements a molecular chain comprising alternating Co{2+} spins organic radical strongly antiferromagnetically coupled. An Arrhenius behavior activation energy Delta=152 K ten decades relaxation time found to be consistent model. We have extended this model take into account ferrimagnetic nature as...

We study the role of defects in ``single-chain magnet'' CoPhOMe by inserting a controlled number diamagnetic impurities. The samples are analyzed with unprecedented accuracy particle induced x-ray emission technique, and ac dc magnetic measurements. In an external applied field system shows unexpected behavior, giving rise to double peak susceptibility. static thermodynamic properties randomly diluted Ising chain alternating $g$ values then exactly obtained via transfer matrix approach....

The field-driven reorientation transition of an anisotropic ferromagnetic monolayer is studied within the context a finite-temperature Green's-function theory. equilibrium state and field dependence magnon energy gap ${E}_{0}$ are calculated for static magnetic $H$ applied in plane along easy or hard axis. In latter case, in-plane magnetization shown to be continuous at $T=0$, agreement with free-spin-wave theory, discontinuous finite temperature $T>0$, contrast prediction mean-field...

The field dependence of the ground state semi-infinite uniaxial antiferromagnets and films is investigated in terms a two-dimensional area-preserving map, where surfaces are introduced as appropriate boundary conditions. For film, calculated for any value number planes very rapid accurate way. system, we show that so-called surface spin-flop does not exist; by energetic arguments, find instability antiferromagnetic configuration leads to an interchange sublattices. A nonhomogeneous instead...

An infinite triangular lattice of classical dipolar spins is usually considered to have a ferromagnetic ground state. We examine the validity this statement for finite lattices and in limit large lattices. find that state rectangular arrays strongly dependent on size aspect ratio. Three results emerge are significant understanding properties: i) formation domain walls energetically favored ratios below critical valu e; ii) vortex always thermodynamic an number spins, but nevertheless such...

Low-temperature specific-heat data obtained in a single crystal of (${\mathrm{C}{\mathrm{H}}_{3})}_{4}$NMn${\mathrm{Cl}}_{3}$ (TMMC) are presented. The experiments were performed variety magnetic field strengths between 0 and 10 T. For fields oriented parallel to the chain axis, linear excitations found adequately describe specific heat. When was perpendicular these alone not sufficient addition nonlinear (solitonlike) required. At low sine-Gordon model appears be adequate but simple ideal...

An exact numerical-transfer-matrix method is used to calculate the thermodynamic properties of an easy-plane Heisenberg ferromagnet with in-plane magnetic field. The results clearly show that often-adopted classical approximation totally inadequate for CsNi${\mathrm{F}}_{3}$ in typical experimental circumstances. In particular, it shown a quantum treatment out-of-plane fluctuations crucial.

Low-temperature specific heat, magnetic susceptibility, and zero-field muon spin resonance ($\ensuremath{\mu}\mathrm{SR}$) measurements have been performed in the quasi-one-dimensional molecular helimagnetic compound $\mathrm{Gd}(hfac{)}_{3}\mathrm{NITEt}$. The heat presents two anomalies at ${T}_{0}=2.19\ifmmode\pm\else\textpm\fi{}0.02\text{ }\text{ }\mathrm{K}$ ${T}_{N}=1.88\ifmmode\pm\else\textpm\fi{}0.02\text{ }\mathrm{K}$, which both disappear upon application of a weak field....

Abstract Ferromagnetic thin films with moderate perpendicular magnetic anisotropy (PMA) are known to support weak stripe domains provided film thickness exceeds a critical value. In this work, we performed both an experimental and theoretical investigation of peculiar phenomenon shown by domains: namely, the reorientation when dc field is applied in plane along direction stripes axis. We focus on bct α ′-Fe 8 N 1− x obtained <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Brillouin light scattering was applied to measure the evolution of spin waves in exchange-coupled [Co/Pd]-NiFe films with out-of-plane/in-plane magnetic anisotropy. Tunable tilting magnetization has important effects on wave frequency gap: a substantial increase is observed decreasing soft NiFe thickness, while seemingly insignificant angles cause strong reduction respect film only hard [Co/Pd] component. The reproduced also samples, increased thickness upper Pd layer, where sudden...

Spin waves propagation in ferromagnetic films, several tens of nanometers thick, have recently received increasing attention, view the development magnonic devices operating GHz range frequencies. A detailed knowledge dispersion curves and spatial characteristics spin-wave modes is preliminary to any technological application, particularly ``mesoscopic range'' (50--200 nm) film thickness, where dipole-exchange may appear spectrum, exhibiting frequency crossing hybridization as a function...

We present numerical simulations, based on a mean-field calculation of the equilibrium configuration, for magnetization reversal process in magnetic multilayers consisting hard (h) phase with large anisotropy, exchange coupled to soft (s) magnetization. Starting from trilayer made $50h/100s/50h$ layers, and using realistic Hamiltonian parameters pertinent epitaxial Sm-Co/Fe films, we separately investigate effect (i) increasing nanostructuration, while maintaining constant overall hard/soft...

The static and dynamic properties of the single-chain molecular magnet [Co(hfac)$_2$NITPhOMe] are investigated in framework Ising model with Glauber dynamics, order to take into account both effect an applied magnetic field a finite size chains. For fields moderate intensity short chain lengths, approximation mono-exponential decay magnetization fluctuations is found be valid at low temperatures; for strong long chains, multi-exponential should rather assumed. oscillating field, much smaller...