H. Hegde

Magnetic properties and synthesis of high iHc Sm‐Ti‐Fe

Mesure du champ coercitif intrinseque de la phase Sm-Ti-Fe en fonction de la composition. Etude des parametres cristallins de cette phase

High-energy product ThMn12 Sm-Fe-T and Sm-Fe permanent magnets synthesized as oriented sputtered films

Binary SmFe12 and Sm(Fe,T)12 films, where T =Ti and V, crystallized into the ThMn12‐type structure, have been synthesized as sputtered films such that the c axes of the crystallites are oriented perpendicular to the film plane. It has been possible to synthesize Sm(Fe,T)12 films which exhibit a very dominant (002) texture with intrinsic coercivities of 5 or more kOe. Such films exhibit flux densities 4πMs of more than 10 kG perpendicular to the film plane. No discernible columnar structure is exhibited so that the static energy product measured perpendicular to the film plane is nearly 21 MGOe.

High‐energy product Sm‐Co‐based sputtered films, crystal texturing, and magnetic properties

Sm‐Co‐based sputteredfilms have been deposited that exhibit a remanence ratio for hysteresis loops measured out of the plane to in the plane of 0.04. These results have been obtained by thermalized sputtering this system in Ar, Ar+Xe mixtures, and in Xe. The use of Xe has allowed a more efficient thermalization of the massive Sm atoms so that a lower total pressure can be used than if Ar were used alone. The use of Ar‐Xe mixtures as the sputtering gas has allowed high‐energy product Sm2(Co, Fe, Cu, Zr)1 7films with the TbCu7‐type crystal structure to be obtained over a much wider range of substrate temperatures and sputteringpressures than has been possible for filmssputtered only in Ar. Filmssputtered in Ar will show a perpendicular to the in‐plane remanence ratio of 0.36 vs 0.04 for Xe. The slope of the hysteresis loops was nearly linear from +18 to −4.5 kOe with values of −0.7%/kOe for the Xe films and a value of −1.2%/kOe for the Ar films. All of these films were directly crystallized onto heated substrates, which is necessary to control the crystal texturing.

The magnetic properties of high iHc Sm‐Co, Nd‐Fe‐B, and Sm‐Ti‐Fe films crystallized from amorphous deposits

Permanent magnet films of the compounds SmCo5, Nd2Fe14B, and a high intrinsic coercive force, iHc, Sm‐Ti‐Fe phase have been prepared by a two‐stage process in which the appropriate compositions were first deposited with a magnetic field applied in the substrate plane, and then subsequently crystallized in situ in this same magnetic field. The resulting samples exhibited high iHc values and specular reflecting surfaces. For the case of SmCo5 and for the high iHc Sm‐Ti‐Fe phase, samples were synthesized that exhibited extreme in‐the‐film‐plane anisotropy. For these SmCo5 and high iHc Sm‐Ti‐Fe samples magnetic measurements, made at room temperature, indicated an in‐the‐film‐plane anisotropy constant of at least 107 erg/cm3 for magnetizing the films in the film plane parallel versus perpendicular to the field that had been applied during the sputter deposition and crystallization. A model is presented based upon the crystallite grain sizes and magnetic alignment energy that correlates the differences in the d...

Cell volume expansion in Sm5(Fe, T)17, T = Ti, V, magnetic phases

Abstract The formation of binary Sm5Fe17 is reported for the first time. The room-temperature i H c observed was 7 kOe. It is also shown that V and Ti replacements for approximately 10% of the Fe yield a systematic and expected expansion of the unit-cell volume. This is interpreted to mean that the Ti and V are replacing part of the iron in the primary magnetic phase.

Film Sm–Co permanent magnets for the biasing of thin permalloy strips

Highly textured Sm–Co‐based permanent magnet films which exhibit in‐plane anisotropy, with thicknesses ranging from 500 A to several microns, have been synthesized on polycrystalline Al2O3 substrates. The textured Sm–Co‐based films of the disordered TbCu7‐type structure were directly crystallized by sputter deposition onto heated substrates. Remanent inductions BR were ≊8 kG, and the intrinsic coercivities, iHc, ranged from 4–10 kOe. The crystallite grain size as a function of film thickness was determined. The use of these films in small scale geometry devices was tested in a sandwich configuration of strips of areal size 7×1 mm2. The Sm–Co films were used to bias Ni81.5Fe18.5 permalloy films. The sandwich permanent magnet was magnetized across its width. The permalloy films were sputter synthesized under conditions very similar to those of the permanent magnet films. Substrate biasing was not used for either the permanent magnet or the permalloy strips. The permalloy films exhibited a well‐defined easy ...

High coercivity Sm2Fe17Nx and related phases in sputtered film samples

High coercivity film samples of the ordered Sm2Fe17Nx phase with intrinsic coercivities, iHc, up to 23 kOe at 293 K, and 35 kOe at 10 K, were synthesized by rf sputtering. Random orientation Sm2Fe17 films were formed by the subsequent crystallization of originally amorphous deposits. The iHc of the original Sm2Fe17 films was 0.75 kOe at 293 K. X‐ray diffractometer traces from 2Θ=28° to 73°, CuKα, exhibited 14 lines. Before nitriding all 14 lines were fit to the 2–17 rhombohedral structure with a=8.555 A, c=12.445 A, with a weighted root‐mean‐square deviation in 2Θ of 0.01°. After nitriding the cell volume increase was ≊7%. Nitriding of the ordered 2–17 films had to be performed in a very narrow temperature range to optimize the magnetic properties. The best magnetic properties were obtained by crystallizing the amorphous deposits in situ at a temperature of ≊900 K for 1 h and then subsequently nitriding in N2 gas at 0.75 atm., at 675–725 K, for 2 h. The room temperature coercivity as a function of the Sm ...

In‐plane magnetized YIG substrates self‐biased by SmCo based sputtered film coatings

Highly anisotropic SmCo based films with the TbCu7‐type structure have been sputter deposited directly onto YIG substrates. The SmCo crystallites have the c axes approximately randomly splayed about the substrate plane such that the easy direction of magnetization of the SmCo film is in the film plane. The in‐plane static energy product of the SmCo film layers was about 16 MG Oe. In‐plane vibrating sample magnetometer hysteresis loops of the SmCo film and YIG substrate exhibit a composite form with the YIG field reversal shifted into the first quadrant by the looping field from the SmCo film layer. Approximately 4×4 mm2 pieces of YIG substrate have been measured to determine the YIG bias field and field required for reverse saturation of the YIG as a function of the SmCo based film layer thickness to YIG substrate thickness. It is observed that for SmCo to YIG thickness ratios greater than 0.22, the looping field from the SmCo film layer is sufficient to saturate the YIG magnetization in the reverse direc...

High anisotropy Nd(Fe,T)12Nx, T=Ti, Mo, films and disordered RE(Fe,Ti) phases before and after nitriding

Highly textured thin films, of ordered Nd(Fe,T)12, T=Ti, Mo, and disordered Nd(Fe,Ti)7 phases, were synthesized by rf sputter deposition. The 1–12 films were highly (002) textured with the c axes oriented perpendicular to the film plane. The disordered Nd‐Fe‐Ti films were fitted to the disordered TbCu7 phase and could be made highly (110) textured with the c axes randomly distributed in the film plane. Nitriding was carried out in N2 at P=400 Torr at ≊450 °C for 2 h. The room‐temperature magnetocrystalline anisotropy fields of the NdFe11Ti and NdFe11Mo films, which were uniaxial, were 10 and 5 kOe, respectively. After nitriding the NdFe11TNx films remained uniaxial, but the anistropy fields increased to 108 and 130 kOe for Ti and Mo, respectively. The iHc perpendicular to the film plane of NdFe11T increased to 5.3 kOe, T=Ti, and to 7.2 kOe, T=Mo, after nitriding. At 293 K, the highest‐energy product of 30.2 MGOe was obtained for a T=Mo nitrided sample. The hysteresis loops of disordered Nd(Fe,Ti)7 and Nd(...

Sputter synthesis of TbCu7 type Sm(CoFeCuZr) films with controlled easy axis orientation

Single phase TbCu7 type films of Sm(CoFeCuZr) have been sputter synthesized for a range of sputter gas pressure, deposition temperature, and two different gas species: Ar and Ar50%Xe. The magnetic and crystallographic properties of these films as a function of sputter deposition parameters have been studied. Films synthesized at temperatures near their crystallization temperatures at sputter gas pressures exceeding 60 mTorr of Ar50%Xe, had a strong c‐axis in‐plane texture. The remanent magnetization ratio for measurement perpendicular to the film plane versus in plane was close to zero for such films. X‐ray diffraction patterns of these films showed only (hk0) type reflections. At gas pressures around 30 mTorr predominant reflection was (111) type. The perpendicular to the in‐plane BR ratio for such films was around 0.55. For films with in‐plane c‐axis texture, in‐plane Br of 9.0 kGauss and coercivities in the range 3–10 kOe were possible. Pressures of Ar and Ar50%Xe correlated roughly in the ratio 1:2 fo...