Coupling Nanostructured CsNiCr Prussian Blue Analogue to Resonant Microwave Fields

Collective spin excitations in magnetically ordered materials are exploited for advanced applications in magnonics and spintronics. In these contexts, conditions for minimizing dissipative effects are sought in order to obtain long living excitations that can be coherently manipulated. Organic and coordination magnetic materials may offer alternative options for their flexibility and low spin-orbit effects. Likewise, ferromagnetic nanostructures provide a versatile platform for hybrid architectures, yet downsizing affects the dynamics of magnetic excitations and needs to be controlled. Here we report a systematic investigation on insulating CsNiCr Prussian blue analogue with different degree of nanostructuring. Combining complementary microwave spectroscopic techniques, we performed magnetic resonance in a wide temperature range across the bulk ferromagnetic transition occurring at TC=90 K. This allows us to monitor key parameters of the spin dynamics through different types of nanostructured samples. We found that, below TC, the Gilbert damping parameter of 10 nm nanoparticles compares well (10-3) with values reported for prototypical inorganic analogues (YIG). Strong coupling with the microwave field of a planar microstrip resonator is then observed for bulk CsNiCr as well as for mutually interacting NPs. These results clarify conditions for the coherent manipulation of collective spin degrees of freedom in nanostructured coordination materials

Magnetocrystalline Anisotropy in Y1-xPrxCo5

A systematic study of the magnetic properties of the system Y1−xPrxCo5 has been carried out in order to clarify the respective role of 3d and 4f anisotropy in the occurrence of first‐order magnetization processes (FOMP) and spin reorientation transitions (SRT) in PrCo5. The competition between Co and Pr anisotropies is responsible for the occurrence of SRT and FOMP, which is indeed observed in Pr‐rich samples. The SRT and the onset FOMP temperatures both increase with increasing Pr content. The anisotropy field, measured by the SPD technique, increases linearly with increasing Pr content. This behavior is not expected and not explainable in terms of a simple addition of Co and Pr anisotropies. A comparison is made with the anisotropy in the systems Y2Co14B and Pr2Co14B

Magnetic order in R2Ni17 intermetallics: a neutron-diffraction investigation

The crystal and magnetic structures of hexagonal intermetallic compounds of the type R2Ni17 with R = Y, Tb, Dy, Ho and Er have been investigated by neutron powder diffraction at 20 and 200 K. The crystal structures at 200 K, which is above the magnetic ordering temperature for these compounds, have been refined and show that they crystallize in the hexagonal Th2Ni17 structure (space group P6(3)/mmc). The magnetic structure at 20 K has a magnetic propagation vector (k) over right arrow = 0 and consists of a ferrimagnetic alignment of R and Ni moments. At 20 K, compounds with R = Tb, Dy and Ho are collinear ferrimagnets with moments aligned in the basal plane of the hexagonal unit cell, whilst the compound with R = Er is an axial collinear ferrimagnet. The low-temperature magnitudes of the R moments at 2b and 2d sites are markedly different, with an almost free ion value at the 2b site, whilst the 2d site moment is substantially reduced from its free ion value. (C) 2002 Elsevier Science B.V. All rights reserved

Magnetic ordering in ErFe6Sn6

We have determined the magnetic structures of the Er and Fe sublattices in ErFe6Sn6 by high-resolution neutron powder diffraction and Mossbauer spectroscopy on the Er-166, Fe-57 and Sn-119 isotopes. The crystal space group is orthorhombic Cmcm. The Fe sublattice is antiferromagnetic with a Neel temperature of 560(5) K and it orders along the [100] direction with a magnetic space group C(p)m'c'm' and a propagation vector [010]. The Fe magnetic moment at 1.5 K is 2.4 +/- 0.6 mu(B). The Er sublattice orders independently of the Fe sublattice at 4.8 +/- 0.4 K and comprises a ferromagnetic mode along [100] and an antiferromagnetic mode along [010], with a propagation vector [0 1/2 0] i.e. cell-doubling along [010]. The magnetic space group of the Er sublattice within the magnetic unit cell is Pbc'm', a subgroup of Cmcm. At 1.5 K the ferromagnetic and antiferromagnetic components of the Er3+ magnetic moment (determined by a combination of neutron diffraction and magnetization measurements) are 5.9 +/- 0.1 and 4.9 +/- 1.5 mu(B), respectively, yielding a net Er moment of 7.7 1.5 AB. The Er3+ magnetic moment derived from Er-166 Mossbauer spectroscopy is 8.5 (1) mu(B)

Neutron diffraction and Mossbauer study of the magnetic structure of YFe6Sn6

We have used time-of-flight (TOF) neutron powder diffraction, and both Fe-57 and Sn-119 Mossbauer spectroscopy over the temperature range 2-600 K to determine the magnetic ordering mode of the Fe sublattice in YFe6Sn6. The crystal structure is orthorhombic (space group Immm). The Fe sublattice orders antiferromagnetically with a Neel temperature of 558(5) K. The TOF neutron diffraction patterns obtained at 4 and 293 K show that the antiferromagnetic ordering of the Fe sublattice is along [100] with a propagation vector q=[010]. The magnetic space group is I(P)m'm'm'. This magnetic structure is confirmed by our Sn-119 Mossbauer spectra. (C) 2000 American Institute of Physics. [S0021-8979(00)18408-7]

Magnetic structure of Nd7Co6Al7

Time-of-flight neutron powder diffraction has been used to determine the magnetic structure of the intermetallic compound Nd7Co6Al7. The thermodynamic, magnetic and electrical properties of this compound indicate that it undergoes a paramagnetic-ferromagnetic transition at 15.5 K, and possesses a magnetic refrigerant capacity of approximately 40 J/kg. The average value of the high field saturation magnetic moment per Nd atom at low temperatures is almost 50% below that of the free ion value. Neutron powder diffraction measurements have been performed at 300 K, in older to confirm the details of the crystal structure, and below the magnetic ordering temperature, at 6 it, in order to establish the nature of the magnetic structure. The high temperature data clearly confirm that Nd,Co,Al, crystallizes in the Pr7Co6Al7 structure (space group P4/mbm). The low temperature data show the presence of reflections at (100), (110), (200) and (210). reflections which are non-existent above the ordering temperature. The presence of the (100) reflection indicates the presence of antiferromagnetic configurations in this system. Models of the magnetic structure for Nd7Co6Al7 will be presented and discussed, (C) 2001 Elsevier Science B.V. All rights reserved

Crystal structure and magnetic ordering of RNi10Si2 compounds

The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R=Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively, corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T-N=4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) mu(B)/Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R=Dy, Ho, Er, and Tin are paramagnetic down to 1.6 K and 3.0 K, respectively

An inelastic neutron scattering determination of the temperature dependence of the 3d-4f exchange interaction in Sm2Fe17

High energy transfer inelastic neutron scattering has been used to investigate the temperature dependence in the range from 20 to 450 K of the intermultiplet transition E-inter in the intermetallic compound Sm2Fe17. The peak due to this transition, observed in the inelastic neutron spectrum, shifts to lower energies with increasing temperature. From the temperature dependence of E-inter, the temperature dependence of the exchange field B-ex acting on the Sm ion has been established experimentally, as the energy of the intermultiplet transition provides a direct value for the exchange field. At the highest measured temperature T=450 K, which is above the Curie point of 389 K for this compound, the transition energy is situated just above the bare spin-orbit splitting for Sm3+. The method utilized in the present investigation offers a rather easy and direct way to determine B-ex in a large range of Sm intermetallics, which form an interesting class of hard magnetic materials. (C) 2002 Elsevier Science B.V. All rights reserved

Magnetic order in RCr2Si2 intermetallics

The magnetic structure and ordering temperatures of three intermetallic compounds which crystallize in the tetragonal ThCr2Si2 structure, TbCr2Si2, HoCr2Si2 and ErCr2Si2, have been determined by neutron diffraction, differential scanning calorimetry and magnetization measurements. The Cr-sublattice orders anti-ferromagnetically with Neel temperatures of 758 K for TbCr2Si2, 718 K for HoCr2Si2 and 692 K for ErCr2Si2. Chromium atoms located at 4d crystallographic sites are aligned anti-parallel along the c-axis, with G(Z)Cr magnetic modes. In contrast with metallic bcc Cr, the refined room temperature value of the ordered Cr moment is anomalously large for all three compounds. No long range magnetic order of the R sublattice in TbCr2Si2 and HoCr2Si2 is observed, whilst the Er sublattice in ErCr2Si2 orders independently of the Cr sublattice below 2.4 K with moments ferromagnetically aligned in the basal plane

Spin-wave dispersion in magnetostrictive Fe-Ga alloys: Inelastic neutron scattering measurements

Fe-Ga alloys of appropriate Ga concentration and heat treatment show a very large enhancement in the tetragonal magnetostriction over that of pure alpha-Fe [lambda(100)(Fe-Ga)similar to 15 lambda(100)(Fe)]. In order to gain further understanding of the extraordinary magnetoelastic characteristics of this system, the spin dynamics of two of these alloys, Fe1-xGax (x=0.160 and 0.225), were studied using inelastic neutron scattering techniques. The correlation of the spin-wave dispersion curve with the lattice constant and atomic radii of solute is examined for this and other Fe alloys