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ABSTRACT: The results of electron spin resonance measurements at high frequencies are reported on the antiferromagnet FeI <sub> 2 </sub> with strong uniaxial anisotropy. We have found new signals whose g value is 16.5 together with the signal with g=7.0 reported before [Fert etal, Solid State Commun. 26, 693 (1978)]. We interpret these electric spin resonance signals as originating from single-ion four magnon and two magnon bound states, respectively. Some of the exchange interaction constants are determined from the analysis of the results. © 2000 American Institute of Physics.
Journal of Applied Physics 06/2000; · 2.17 Impact Factor
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ABSTRACT: Low-temperature high-magnetic-field far-infrared spectroscopy and electron-spin-resonance measurements have been performed on single crystals of the cubic perovskite KNiF3. We found the absorption at 48.7±0.3 cm-1 observed by Richards [P. L. Richards, J. Appl. Phys. 34, 1237 (1963)] that was attributed to antiferromagnetic resonance (AFMR) is not magnetic in origin. Instead, a different absorption is well fit by a theory of AFMR with uniaxial anisotropy. Analysis yields an anisotropy energy of 8.7×10-3 cm-1. The ratio between the anisotropy field and the exchange field is 2.4×10-5. Thus, KNiF3 is an excellent example of a Heisenberg antiferromagnet.
Phys. Rev. B. 02/1999; 59(9).
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ABSTRACT: We describe a case of juvenile systemic granulomatosis in a 22-year-old woman. The rash consisted of purple papules and first appeared at the age of one year. She had persistent symmetrical painless boggy tenosynovitis with minimal roentgenographic changes and chronic granulomatous symptoms. Uveitis resulted in visual impairment. She also had granulomatous changes in her vessels. Renal impairment developed; however, neither renal artery stenosis nor hypercalcemia was found. Clinical features included the development of premature aging with alopecia, which differed from the previously reported progeria syndrome. Poikiloderma may cause a prematurely aged appearance. Our report expands the clinical spectrum of systemic granulomatosis to include the development of premature aging with alopecia.
The Journal of Rheumatology 03/1997; 24(2):393-5. · 3.69 Impact Factor
