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Pure YBa 2 Cu 3 O 7− δ (YBCO) pellet and many pellets of YBa 2 Cu 3 O 7− δ /Y 3 Fe 5 O 12 (YBCO/YIG) of different concentrations of YIG were prepared by pressing nanoparticles into disks of 5 mm of diameter and 0.5 mm of thickness. X-ray diffraction (XRD) with CoK α radiation was used to check the phase formation and to determine the mean crystallite sizes from the half-width X-ray peaks using the Scherrer relation. Magnetization measurements vs. temperature T and applied field H were performed using a conventional magnetometer within the temperature range 4.2–110 K and in magnetic fields up to 10 T. The field was applied parallel to the pellet axis. Our results confirm the superconductivity and ferromagnetism coexistence in nanoparticles of YBCO at 4.2 K. For H less than a threshold field H ⁎ , the superconducting nano-domains are prevalent in the sample. When the field increases beyond H ⁎ , the spins of the superconducting nano-domains line up along the direction of the applied field to create a ferromagnetism phase that reinforces the ferromagnetic nano-domains. The present experimental findings corroborate Kopp et al.'s claims that superconductivity and ferromagnetism in singlet superconductors such as cuprates do not exist uniformly but are phase-separated in nano-domains.

The blending of magnetic elements or compounds into a superconducting matrix has a direct effect on the physical properties of the latter and provides precious information on the superconductivity mechanisms, the spin/vortex interaction and the vortex pinning. To our knowledge, no study of the addition of nanoparticles of yttrium iron garnet Y3Fe5O12 (called commonly YIG) in the yttrium, barium and copper oxide YBa2Cu3O7−δ (well known under the YBCO appellation) nanometrical matrix has been performed up to the present time. The YBCO and YIG powders have been elaborated by a conventional ceramic process. The obtained products have been characterized by magnetization measurements, X-ray diffraction and optical microscopy. The used ways to reduce their grain sizes below 50 nm and to mix them avoiding the formation of grain crowds have been explained. Their nanometrical sizes have been confirmed by atomic force microscope analysis. Eight pellets have been elaborated. The thermal variations of zero field cooled magnetizations, in a residual field of 44 G, have shown that the introduction of 5 and 9% in weight of a non-superconductor material (YIG) into a superconducting matrix (YBCO) has reduced the TC only by 1 K for a ybcoyig5% pellet and 1.57 K for a ybcoyig9% one, comparatively with the ybcopur reference pellet’s TC. In another way, our results have shown that the incorporation of YIG in very low quantities, between 0 and 0.5% in weight of YIG, increases the value of the critical current JC of a ybcopur pellet (and, so, the vortex pinning). By fitting our experimental points starting from 0.5% in weight of YIG, an empirical law of the JC variation versus added YIG percentage is suggested.

PrBaCuO and YBaCuO cuprate materials were prepared from cooper, barium peroxide, and yttrium/praseodymium oxide by SHS and standard solid-state synthesis. SHS reactions were carried out using relatively large cooper particles (< 63 im) to obtain small product samples (13 mm in diameter). High ambient temperature was used to stabilize a combustion front in the ignited pellets. Explored was the effect of cooper particles size, starting density, and ambient temperature on phase evolutions in synthesized materials.

Hematite ( α - Fe 2 O 3 ) and magnetite (Fe 3 O 4 ) powders, milled for various times up to 10 hours by a high energy ball milling technique, were structurally and magnetically characterized by X-ray diffraction and magnetic measurements in magnetic field up to 10 T in the 2 K–300 K temperature range. From X-ray diffraction line analyses, it is found that when the milling time is increased, the grain size of α - Fe 2 O 3 particles falls down to about 15 nm, and the induced strains and distortions increase up to 0.9% at 10 hours of milling. The ZFC-FC magnetization curves of the milled samples for 1 hour, with an applied field of 5 mT, show that superparamagnetism is present, but with a blocking temperature well above 300 K. The magnetization at saturation increases to a maximum of 0.78 Am 2 /kg, while the coercive force falls rapidly to a constant value after a milling time of 5 hours. Magnetite powders, milled up to 10 hours, transform partially to hematite, leading to a decrease of the magnetization at 300 K. A correlation between the microstructural evolution of the milled sample can be made with its magnetic properties.

Amorphous (Fe 50 Co 50 ) 62 Nb 8 B 30 powder mixture was prepared by mechanical alloying from elemental Fe, Co, B and Nb powders in a planetary ball mill under argon atmosphere. Structural, thermal and magnetic properties were performed on the milled powders by means of X-ray diffraction, differential scanning calorimetry and magnetic measurements. The amorphous state is reached after 125 h of milling. The excess enthalpy due to the high density of defects is released at temperature below 300 °C. Crystallisation and growth of crystal domains are the dominating processes at high temperatures. The saturation magnetisation decreases rapidly during the first 25 h of milling to about 15.24 A m 2 /kg and remains nearly constant on further milling. Coercivity, H c , value of about 160 Oe is obtained after 125 h of milling.

The Dunkirk RH-OB was one of the first in Europe and started in 1984. Since the beginning, its production has increased steadily and the proportion of decarburization treatments has become predominant. This performance has been made possible thanks to investments like an increased capacity of the vacuum pump and an enlargment of the diameter of the snorkel and to improvements in the process. The carbon level and the treatment time have been reduced continuously.

The serotonergic neurotransmission is known as a neuromodulatory system exerting its activity in the central nervous system (CNS) as well as at the periphery. The anatomical and morphological organization of the system based on a marked centralization of the cellular bodies and the large, almost ubiquitary, presence of axonal projections of the neurons is in good agreement with this modulatory role. Furthermore, a very high number of varicosities located along the axonal branches are capable of releasing serotonin (5-HT). The amine stimulates a number of different specific receptor types which allows 5-HT to exert different activities on its various cellular targets. Among these receptors, the 5-HT1B subtypes play a particular role as they are autoreceptors located on 5-HT neurons terminals and heteroreceptors located on non-serotonergic terminals where they control the release of the neurotransmitter. 5-HT-moduline, an endogenous tetrapeptide, regulates the efficacy of these 5-HT1B receptors, hence, is able to control the serotonergic activity in a synchronous manner for the various varicosities from a single neuron and thus may favour the differential effect of that neuron on distinct cerebral functions. Accordingly, the peptide allows the 'fine tuning' of the cerebral activity by the serotonergic system to elaborate the response given by the brain to a particular stimulus, that is, stress situations. At the periphery, the serotonergic system also appears to possess a regulatory activity via 5-HT1B receptors. In particular, the receptors located on immunocompetent cells control their activity and are themselves regulated by 5-HT-moduline likely originating from adrenal medulla and released after acute stress. The serotonergic system appears to play a major role in the reciprocal signalling existing between the neuronal and the immune system. The participation of 5-HT-moduline is likely in physiological functions as well as in pathological disorders affecting central and peripheral activities.

Magnetisation measurements have been performed on spherical single crystals of dysprosium iron garnet (Dy3Fe5O12) in high dc magnetic fields up to 16 T applied along the three principal crystallographic directions 〈111〉, 〈110〉 and 〈100〉. The magnetic phase transitions near the inversion (or compensation) temperature TI between the collinear and the field induced canted magnetic structures are observed and the different associated magnetic phase diagrams precisely determined in the (H,T) plane. The mean exchange field acting on the Dy ions and the effective anisotropy field are deduced to be (12.9±0.2) T and (1.2±0.1) T respectively. Above 228.2±0.5 K, only the collinear magnetic phase exists for all the directions. These results are compared to previous high pulsed magnetic fields data.

The magnetic properties have been investigated in some Sm-Co and Er-Co amorphous alloys. The samples have been obtained by r-f sputtering on different substrates. Those on glass and silica substrates have been used for structural (X-ray diffraction) and compositional (SEM) analysis. Magnetisation process (4 K

5-carboxamidotryptamine (5-CT)-insensitive binding sites labelled by [3H]5-hydroxytryptamine (5-HT) in the presence of 100 nM 5-CT and 100 nM mesulergine, were examined by semi-quantitative autoradiography in rat brain. Under these conditions most of the labelled sites correspond to 5-HT1E and 5-HT1F sites. The 5-CT-insensitive binding is located mainly in cortical layer V, caudate-putamen, interpeduncular nucleus and claustrum. In cortex and caudate-putamen, a large proportion of 5-CT-insensitive sites is displaced by 250 nM sumatriptan and can be attributed to the presence of 5-HT1F receptors. A low, but significant, level of displacement by sumatriptan was observed in the choroid plexus. Lesions of serotonergic neurones by intracerebroventricular 5,7-dihydroxytryptamine injection does not significantly modify the densities of 5-HT1E or 5-HT1F binding sites. Our findings suggest that the 5-HT1F receptor has a limited distribution in rat brain, mainly located on non-serotonergic neurones.

Glycosyl phosphate derivatives of N-acetyl-5-hydroxytryptamine were synthesized from 2-deoxy-D- glucose, D-glucose and D-mannose. These brain transport vectors for the precursor of melatonin were tested for locomotion on mice : with intracerebral and peripheral administrations, the prodrugs exhibited an inhibitory effect, whereas the same effect was observed for melatonin or its precursor only with an icv injection.

The results of inelastic neutron scattering (INS) and magnetization measurements of the Nd 2 CuO 4 compound are presented. The theoretical analysis of the INS data allowed to determine the set of crystal field (CF) parameters describing well also the magnetization data in this compound. It is shown that one has to include J -mixing as well as intermediate coupling into the considerations in order to arrive at a reliable set of CF parameters.

We present new evidence that a cross flow of sublattices of helical flux lines takes place when a current is induced with a component along the flux lines

Neutron powder diffraction and magnetization measurements have been performed in stoichiometric Pr2NiO4+δ(δ≈0), which at room temperature (RT) is orthorhombic (Bmab). Ni2+ becomes three dimensionally (3D) antiferromagnetically ordered atT N ≈325K, with a propagation vectork=[100], and spins oriented along thea axis (parallel to the propagation vector). The magnetic structure belongs to theΓ 7g (−−+)-representation (g x mode, Shubnikov groupB pmab') ofBmab, and a magnetic moment of 1.5μ B is measured at 155K. This compound undergoes two different structural phase transitions. First, going down in temperature, Pr2NiO4 transforms by a first order phase transition from orthorhombic (Bmab) to tetragonal (P42/ncm) atT c1≈115K. At high temperature, we can predict a transformation from orthorhombic (Bmab) to tetragonal (I4/mmm) in a continuous way. The extrapolated temperature for this second structural transition isT c2≈1500±100K. The low temperature structural transformation allows a change in the magnetic structure which forT

We have studied Co—Cu single crystal superlattices by neutron diffraction and bulk magnetization measurements. Special care was paid to the proper orientation of the sample for the magnetization experiments, in order to distinguish between in-plane anisotropies. Neutron diffraction data shows a pattern from the new superstructure (periodicity ΛSL), as well as a second diffraction pattern of magnetic origin with 2ΛSL periodicity. The antiferromagnetic (AF) ordering was confirmed by polarized neutron diffraction. There is a peculiar dependence on the applied external field. At moderate magnetic fields (6–8 kOe), the AF alignment is reversed to ferromagnetic. For lower magnetic fields, there is a complicated magnetic behavior, with strong competition between in-plane anisotropies and exchange coupling energy, which produce intermedium magnetic orderings.

The magnetization distribution in sputtered random-anisotropy TbCo 3 amorphous films was observed by transmission electron microscopy at room, low and high temperature. In the as-grown films, about 8 x 10 -8 m thick, a disordered structure on a scale of 10-7 m, consistent with the Imry and Ma picture for a correlated spin glass, is observed at room temperature. This structure is unaffected by cooling but is irreversibly and progressively simplified on heating. Domain wall contrast is reversed, with no change in wall positions, when going through the compensation temperature of about 270 K. In thinned fragments, the domain structure is qualitatively different, due to terbium loss near the surfaces.

Linear thermal expansion measurements have been performed up to 70 K with a capacitive dilatometer on a DyBa 2 Cu 3 O 7− δ polycrystalline sample which has been characterized by SEM micrography and magnetic Meissner effect. We report first some of these results which show the absence of any magnetically ordered impurity phase at low temperature in our sample. The thermal expansion also does not show the anomaly at 11 K previously reported, so we suggest that this anomaly was rather due to the magnetic ordering of an impurity phase than resulting from crystal field effects.

The single particle switching field and its temperature dependence of an isotropic sintered NdFeB hard magnet are determined by a new method using both the perpendicular and the parallel component of the susceptibility related to the applied field. The results can be fitted by a simple 1/cos /spl thetav/ law for /spl Theta/ >

Static power converters are being used increasingly in power system applications. The power semiconductor switches within these converter systems accommodate power system fault overvoltages. Significant cost reductions can be attained by reducing the magnitude of power system fault currents. In this paper, the authors propose the use of a novel passive current limiter to accomplish this task. The limiter consists of two magnetic devices connected in series and in magnetic counter opposition to each other. Each magnetic device consists of three slices of NdFeB permanent magnet material sandwiched between the three end poles of two ferrite E cores. Experimental and finite element results are presented and are found to be in good agreement with each other. The need for 3D modeling in the future is demonstrated. The operating characteristics of the current limiter are experimentally verified using a scaled down version of a power system.

The serotonergic system is one of the aminergic neurotransmitter systems participating in the maintenance of homeostasis of the organism in mammals; accordingly, it regulates the activity of various cerebral functions to organize adapted responses of the brain to environmental stimuli. The regulatory activity of the serotonergic system itself is modulated by an endogenous mechanism based on an allosteric interaction involving a newly discovered peptide, 5-HT-moduline, and the 5-HT1B receptor which, as an autoreceptor, controls the release of 5-HT from serotonergic neuron terminals. 5-HT-moduline specifically interacts with 5-HT1B receptors at nanomolar concentrations resulting in the desensitization of the receptor. As 5-HT1B autoreceptors have an inhibitory effect on the release of 5-HT, 5-HT-moduline ultimately increases its release. The peptide is characterized by several criteria which correspond to those of a neurotransmitter, strongly suggesting that 5-HT-moduline is a novel neuropeptide locally controlling serotonergic activity. 5-HT-moduline is released in various parts of the brain, particularly under conditions of stress; moreover, its deactivation by specific antibodies in mice induces changes in the behavior of the animal. These results strongly suggest that the peptide may play a role in the physiopathology of central nervous system disorders in mammals, particularly in conditions related to stress and anxiety. Furthermore, the fact that 5-HT-moduline increases the release of 5-HT suggests that synthetic drugs which recognize the 5-HT-moduline binding site on 5-HT1B receptors and mimic the effect of the peptide, may have antidepressant properties by increasing the release of 5-HT.

A very simple analytical scaling model has been developed for superparamagnetic particles submitted to a magnetic field larger than the dipolar-interaction field (≈ 1 kOe). This model, valid at any temperature, leads to two scaling forms corresponding to two physical regimes (high field and low field regimes). This model allows to fit very well the measured magnetization curves of Fe nanoparticles epitaxed on an Al 2 O 3 matrix, in the temperature, field and Fe concentration ranges of 2–300 K, 1–60 kOe and 2 to 10% respectively. The fitting parameters are unique (with small error bars) and their values can easily be connected with the physical and chemical properties of the samples (shape of the size distribution, its iron concentration dependence, existence of a shall of Fe 3+ surrounding Fe 0 /Al 2 O 3 interface).

We have investigated a sintered Gd 1.85 Th 0.15 CuO 4 sample in a SQUID magnetometer under pressure up to 10 kbar. From high-field magnetic measurements, we have deduced a large decrease under pressure of the internal field associated to the weak ferromagnetism of the Cu sublattice. We have studied by magnetic susceptibility measurements in low field the pressure effect on the Neel temperature, on the magnetic ordering temperature of the rate earth and on the intermediate spin reorientation temperature. Possible implications for electron-doped superconductivity of related compounds are discussed.

The aim of this work is to show that, in order to produce high-quality metallic superlattices, the major requirements are to have an accurate control of the growth process and to use very flat, well ordered substrates. To this end, the growth of Co and Cu on Cu(100) has been studied from its very early stages, by means of Thermal Energy Atom Scattering (TEAS). Also, different Co Cu superlattices have been produced, and studied by neutron diffraction and SQUID magnetometry. They show good crystallinity, with the cobalt layers magnetized in plane and ordered antiferromagnetically. The magnetic moment of the cobalt atoms coincides with that of bulk fcc cobalt.

5-HT1B receptors play a specific role as one of the many receptors regulating serotonergic activity. This endogenous peptide was recently isolated and characterized. Specific interaction has been demonstrated. 5-HT-moduline appears to be implicated in central nervous system response to various stimuli, particularly stress. It might play an important role in adaptation/inadaptation mechanisms (stress, anxiety, depression).

The serotonergic system controls the activity of neurotransmissions involved in numerous physiological functions. It is also thought to be crucially implicated in various pathologies, including psychiatric disorders such as depression, anxiety, and aggressiveness. The properties of 5-hydroxytryptamine (5-HT)-moduline, a novel endogenous peptide, have been tested in vitro and in vivo. Binding studies have shown that the peptide specifically interacts with 5-HT1B/1D receptors via a noncompetitive mechanism corresponding to a high apparent affinity (EC50 = 10(10) M). The interaction was shown in rat and guinea pig brain tissues and in cells transfected with either 5-HT1B or 5-HT1D beta receptor gene. [3H]5-HT-moduline binds to a single population of sites in mammalian brain (Kd = 0.4 nM in rat, Kd = 0.8 nM in guinea pig) as well as in transfected cells expressing the 5-HT1B or the 5-HT1D beta receptors (Kd = 0.2 and 0.6 nM, respectively). Furthermore, the binding is clearly specific of the LSAL sequence. Autoradiographic studies showed an heterogeneous brain distribution of this site. The interaction of 5-HT-moduline with the 5-HT1B/1D receptor corresponds to a decrease in the functional activity of the receptor (i.e., a decrease in the inhibitory effect of a 5-HT1B agonist on the evoked release of [3H]5-HT from synaptosomal preparation). It was also shown that 5-HT-moduline possess an in vivo effect in the social interaction test in mouse. Finally, it was demonstrated that 5-HT-moduline was released from brain synaptosomal preparation by a K+/Ca(2+)-dependent mechanism. In conclusion, 5-HT-moduline is a novel endogenous peptide regulating the serotonergic activity via a direct action at presynaptic 5-HT receptor. It may play an important role in the physiological mechanisms involving the serotonergic system, particularly in mechanisms corresponding to the elaboration of an appropriate response of the central nervous system to a given stimulus.

International audience; Les interactions fonctionnelles entre les systemes immunitaire (SI) et nerveux (SN) sont possibles grace a la presence de mediateurs et de recepteurs communs aux 2 systemes. Panni les cytokines, I'interleukine-1 (IL-i) est un puissant modulateur des 2 systemes. Nous avons pu caracteriser des recepteurs IL-1 type I dans le cerveau de souris au niveau de neurones (gyrus dentele de l'hippocampe), de structures vasculaires (plexus choroYdes et vaisseaux) et neuroendocriniennes (hypophyse). Ces recepteurs IL-1 centraux sont profondement modifies par l'administration peripherique de produits bacteiiens (LPS) ou de virus (rage) alors que les reepteurs de l'hypophyse ne sont pas modifies. Ces modulations sont liees a une augmentation de la synthese locale de l'IL-1 (ARNm) dans le SN. Le stress et les glucocorticoides sont des inhibiteurs puissants des fonctions immunitaires en particulier par l'intermediaire d'une inhibition de la synthese de l'IL-1. Ces 2 facteurs augmentent l'expression des recepteurs IL-i hypophysaires sans modifier les recepteurs centraux, ce qui souligne l'autonomie des retgulations centrales par rapport aux regulations peripheriques. La presence de recepteurs de l'IL-1 sur des structures nerveuses (cortex, hippocampe) et l'action immuno-suppressive rapide d'injection intra-cerebro-ventrculaire de faibles doses de l'IL-1 laissent penser que ces recepteurs jouentun r8le important dans les retgulations homeostasiques entre le SN et le SI. En conclusion, le SN exprime des mediateurs et des recepteurs typiques du SL Leurs regulations semblent se realiser de fapon autonome par rapport aux regulations peripheriques et leurs roles dans les interactions SN/SI restent a preciser.

Genes, constituted by the deoxyribonucleic acid (DNA) contain all the genetic information of a cell. DNA is a double helix consisting of two antiparallel polynucleotide chains where each nucleotide is composed of the association between a base, a sugar and a phosphate group. The chains are associated by hydrogen bonds between the bases. Guanine bonds specifically with cytosine while adenine bonds specifically with thymine. The sequence of DNA is related to the sequence of protein by the genetic code. Each aminoacid is represented by a codon that consists of a nucleotide triplet. Information is expressed by a two-step process. The first step, transcription generates a single-stranded ribonucleic acid called messenger RNA (mRNA) (where a uracil base is present instead of a thymine) which acts as an intermediate molecule. In this step, RNA splicing is one of the maturation processes consisting of joining the exons by removing the introns of the precursor RNA molecule. The second step, translation, converts the nucleotide sequence into the sequence of aminoacids. Since the 1970s, the progress in DNA technology consisting of the development of molecular cloning, DNA library construction and sequencing methods, has made it possible to isolate and analyze specific genes directly from the genome. A sequence of genomic or complementary DNA (cDNA) is cloned by inserting it into a vector (plasmid or phage) that can replicate independently in bacteria. Before cloning, genomic DNA is digested into fragments by restriction enzymes (endonucleases cleaving specific sequences within double-stranded DNA) whereas RNA sequences are copied into cDNA by reverse transcriptase.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental observations indicate that 5-HT receptors are located on a variety of immunocompetent cells and that 5-HT participates in controlling functional activity within the immune system, and in particular its natural killer (NK) arm. Reciprocally, changes in immune responsivity are able to alter CNS 5-HT activity. Thus, 5-HT appears to play a key role in the interactions between the CNS and the immune system.

Magnetic properties of Ni3Al-Fe alloys disordered by mechanical grinding have been measured both at low and high temperatures. While the equilibrium high temperature disordered state is paramagnetic, our metastable disordered state is ferromagnetic. Magnetic moment and Curie temperatures of the disordered state have been determined for several compositions. They are lower than those of the ordered state and vary strongly with concentration and especially with Fe content The weaker ferromagnetism of the disordered state is attributable to a lower number of Fe-Ni nearest neighbors in the disordered fcc state.

The G protein coupled serotonin (5-HT) receptors, with seven membrane spanning domains, form a multigene family of which several members have been cloned and sequenced. The presence of 5-HT1D binding sites to our knowledge has not yet been reported in mouse. Here we describe the cloning and sequencing by the polymerase chain reaction (PCR) method of two 5-HT1D receptor sequences of the third cytoplasmic loop in mouse, strongly suggesting the existence of two 5-HT1D receptor genes, located on chromosome 4. A homologous sequence to one of them was cloned in guinea pig.

Coercivity, Hc, is one of the most useful magnetic parameters which can be used to nondestructively characterize the microstructure or mechanical properties of ferromagnetic materials (1–2). However, for in-the-field applications it is generally not possible or practical to have materials of ideal geometry, i.e. slender cylinders around which one can wind coils to measure magnetic induction and deduce Hc. Other techniques must therefore be devised. The most useful are based on locally magnetizing the material studied, while monitoring either eddy current response or Barkhausen noise (BN) (3, 4). These techniques, however, are limited to thin layers because of skin depth effects. Recently Dobmann and Pitsch5 have shown empirically that from analysis of the harmonic content of the surface tangential field, H(t), it is possible to obtain a field, HCO which is strongly correlated to Hc. This technique, which is based solely on analysis of the tangential field, has the advantage of probing much greater depths than is practical using eddy currents or BN.

Ordering of the disordered state (obtained by cold-working or by meltspinning) of L12 type Ni,AI,Fe alloys has been monitored by calorimetric, magnetic and X-ray diffraction measurements .It is found that the magnetic moment per atom of the Ni,Al,Fe alloys in the γ-disordered state is about half of that of the LI2 -γ'state. Magnetic measurements such as ours constitute a new tool for studyingthe γ→γ' transition below the Curie temperature.

A high quality of (Tl0.5Pb0.5)Sr1.8Ba0.2Ca2Cu3O9−δ ceramic with Tc≈120 K has been prepared and studied by magnetic measurements. The field and temperature dependence of the intragranular critical current are deduced from the Bean model. For this single (insulating) Tl-O layer material, Jc has a value of the order of 2.105 A/cm2 at 80 K and in a field of 1 T. The mean irreversible line determined from hysteresis loops is also compared to the ones obtained from ac susceptibility measurements.

Magnetization measurements in Pr2NiO4 single crystals were made up to 70kOe, for different orientations of the applied magnetic field with respect to the crystallographic axes, in the range from 1.5 to 300K. The Ni sublattice becomes antiferromagnetically ordered at TN=325K, as reported from previous neutron diffraction experiments1. There is also a structural transition at TC1=117K1, which allows a ferromagnetic component in the low temperature phase. Below TC1 different magnetic anomalies are observed, which have been interpreted as spin reorientations. Finally at low temperature the Pr sublattice is also ordered. Four different transitions induced by the external applied magnetic field parallel to the c-axis are visible in the range from 0 to 70 kOe, for T

The static magnetization and magnetic susceptibility anisotropy of (TMTTF)2 X(where X = AsF6 and SbF6) have been investigated between 3 and 300 K for magnetic field strengths up to 50 kG. A spin Peierls phase transition is observed in AsF6 salt around 11 K, whereas in the (TMTTF)2 SbF6 compound an antiferromagnetic (AF) transition is detected around 7 K.