We have published the following papers on the subject:<\/h3>\n\n\n- T.Leviant, A.Keren, E.Zeldov, and Y.Myasoedov, Quantum ignition of deflagration in the Fe8<\/sub> molecular magnet<\/a>, Phys. Rev. B., 90, (2014) 134405.<\/li>\n<\/ul>\n
Abstract:
\nWe report spatially resolved, time-dependent, magnetization reversal measurements of an Fe8<\/sub> single molecular magnet using a microscopic Hall bar array. We found that a deflagration process, where molecules reverse their spin direction along a moving front, can be ignited quantum mechanically (T<\/i> \u2192 0) at a resonance field, with no phonon pulse. The avalanche front velocity is of the order of 1 m\/s and is sensitive to field gradients and sweep rates. We also measured the thermal diffusivity \u03ba<\/em> in Fe8<\/sub>. This allows us to estimate the “flame” temperature.<\/p>\n\n- T.Leviant, S.Hanany, Y.Myasoedov, and A.Keren, Testing the radiation emanating from the molecular nanomagnet Fe8<\/sub> during magnetization reversals<\/a>, Phys. Rev. B., 90, (2014) 054420.<\/li>\n<\/ul>\n
Abstract:
\nPhotons emitted by transition between the discrete levels of single molecular magnets might obey the elementary condition for Dicke’s super-radiance. We investigate this possibility in the Fe8<\/sub> molecule where magnetization jumps are known to occur at discrete magnetic-field values. We found energy bursts each time the molecule undergoes a magnetization jump, confirming their quantum nature. A series of tests indicated that photons carry out the energy and that indeed these photons obey the elementary conditions for super-radiance.<\/p>\n\n- O.Shafir, A.Keren, S.Maegawa, M.Ueda, and E.Shimshoni, Magnetic quantum tunneling in Fe8 with excited nuclei<\/a>, Phys. Rev. B., 82, (2010) 014419.<\/li>\n<\/ul>\n
Abstract:
\nWe investigate the effect of dynamic nuclear-spin fluctuation on quantum tunneling of the magnetization (QTM) in the molecular magnet Fe8<\/sub> by increasing the nuclei temperature using radio frequency (rf) pulses before the tunneling measurements. Independently we show that the nuclear-spin-spin relaxation time T2<\/sub> has strong temperature dependence. Hence, in principle, the rf pulses should modify the nuclear-spin dynamic. Due to very long spin-lattice relaxation time, the rf pulses do not change the electrons spin temperature. Nevertheless, we found no effect of the nuclear-spin temperature on the tunneling probability. This suggests that in our experimental conditions only the hyperfine-field strength is relevant for QTM. We demonstrate theoretically how this can occur.<\/p>\n\n- O.Shafir and A.Keren, Electromagnetic radiation emanating from the molecular nanomagnet Fe8<\/a>, Phys. Rev. B., 79, (2009) 180404(R).<\/li>\n<\/ul>\n
Abstract:
\nPhotons emitted by transition between the discrete levels of single molecular magnets might obey the elementary condition for Dicke’s super-radiance. We investigate this possibility in the Fe8<\/sub> molecule where magnetization jumps are known to occur at discrete magnetic-field values. We found energy bursts each time the molecule undergoes a magnetization jump, confirming their quantum nature. A series of tests indicated that photons carry out the energy and that indeed these photons obey the elementary conditions for super-radiance.<\/p>\n\n- A.Keren, O.Shafir, E.Shimshoni, V.Marvaud, A.Bachschmidt and J.Long, Experimental Estimates of Dephasing Time in Molecular Magnets<\/a>, Phys. Rev. Lett., 98, (2007) 257204.<\/li>\n<\/ul>\n
Abstract:
\nMuon spin relaxation measurements in isotropic molecular magnets (MM) with a spin value S<\/i> ranging from 7\/2 to 27\/2 are used to determine the magnitude and origin of dephasing time \u03c4\u03d5<\/sub><\/i> of molecular magnets. It is found that \u03c4<\/i>\u03d5<\/i><\/sub> ~ 10 nsec with no S<\/i> or ligand dependence. This indicates a nuclear origin for the stochastic field. Since \u03c4<\/i>\u03d5<\/i><\/sub> is a property of the environment, we argue that it is a number common to similar types of MM. Therefore, \u03c4<\/i>\u03d5<\/i><\/sub> is shorter than the Zener and tunneling times of anisotropic MM such as Fe8<\/sub> or Mn4<\/sub> for standard laboratory sweep rates. Our findings call for a stochastic Landau-Zener theory in this particular case.<\/p>\n\n\n- O.Shafir, A.Keren, S.Maegawa, M.Ueda, A.Amato, C.Baines, Demonstrating multibit magnetic memory in the Fe8 high-spin molecule by muon spin rotation<\/a>, Phys. Rev. B, 72, (2005) 092410.<\/li>\n<\/ul>\n
Abstract:
\nWe develop a method to detect the quantum nature of high-spin molecules using muon spin rotation and a three-step field cycle ending always with the same field. We use this method to demonstrate that the Fe8<\/sub> molecule can remember six (possibly eight) different histories (bits). A wide range of fields can be used to write a particular bit, and the information is stored in discrete states. Therefore, Fe8<\/sub> can be used as a model compound for multibit magnetic memory. Our experiment also paves the way for magnetic quantum tunneling detection in films.<\/p>\n\n\n- Z. Salman, A Keren, S. Megeawa, M. Ueda, O. Shafir, B. Barbara, C. Baines, Probing magnetic quantum tunneling in Fe8<\/sub> with muons<\/a>, Physica B 326, (2003) 480-483.<\/li>\n<\/ul>\n
Abstract:
\nWe present a muSR<\/span> study of the Fe8<\/sub> molecules from which an evidence of quantum tunneling of the magnetization (QTM) can be seen, in the form of drastic changes in the local field experience by the muon<\/span>.<\/span><\/p>\n<\/div>\n\n\n- Z. Salman, A Keren, P. Mendels, V. Marvaud, A. Scuiller, M. Verdaguer, J. S. Lord, and C. Baines, Dynamics at T–>0 in the half-integer isotropic high spin molecules<\/a>, Phys. Rev. B 65,\u00a0 (2002) 132403.<\/li>\n<\/ul>\n
Abstract:
\n![\"PRBimg23\"](\"http:\/\/phsites.technion.ac.il\/magnetic\/wp-content\/uploads\/sites\/26\/2015\/02\/PRBimg23-150x150.png\")
We investigate the dynamical spin-spin auto-correlation function of the isotropic high spin molecules CrCu6<\/sub>(S=9\/2),\u00a0 CrNi6<\/sub><\/span> (S=15\/2) and CrMn6<\/sub> (S=27\/2), using magnetization, muSR<\/span> and NMR measurements. We find that the field autocorrelation time tau<\/i><\/span> of the molecule’s spin at zero and low fields is nearly temperature independent as T –> 50 mK<\/span><\/span>, indicating that it is induced by a quantum process. The high temperatures tau<\/i><\/span> is very different between the molecules. Surprisingly, it is identical (~10 nsec<\/span>) at base temperature.<\/p>\n<\/div>\n
- \n
- T.Leviant, A.Keren, E.Zeldov, and Y.Myasoedov, Quantum ignition of deflagration in the Fe8<\/sub> molecular magnet<\/a>, Phys. Rev. B., 90, (2014) 134405.<\/li>\n<\/ul>\n
Abstract:
\nWe report spatially resolved, time-dependent, magnetization reversal measurements of an Fe8<\/sub> single molecular magnet using a microscopic Hall bar array. We found that a deflagration process, where molecules reverse their spin direction along a moving front, can be ignited quantum mechanically (T<\/i> \u2192 0) at a resonance field, with no phonon pulse. The avalanche front velocity is of the order of 1 m\/s and is sensitive to field gradients and sweep rates. We also measured the thermal diffusivity \u03ba<\/em> in Fe8<\/sub>. This allows us to estimate the “flame” temperature.<\/p>\n- \n
- T.Leviant, S.Hanany, Y.Myasoedov, and A.Keren, Testing the radiation emanating from the molecular nanomagnet Fe8<\/sub> during magnetization reversals<\/a>, Phys. Rev. B., 90, (2014) 054420.<\/li>\n<\/ul>\n
Abstract:
\nPhotons emitted by transition between the discrete levels of single molecular magnets might obey the elementary condition for Dicke’s super-radiance. We investigate this possibility in the Fe8<\/sub> molecule where magnetization jumps are known to occur at discrete magnetic-field values. We found energy bursts each time the molecule undergoes a magnetization jump, confirming their quantum nature. A series of tests indicated that photons carry out the energy and that indeed these photons obey the elementary conditions for super-radiance.<\/p>\n- \n
- O.Shafir, A.Keren, S.Maegawa, M.Ueda, and E.Shimshoni, Magnetic quantum tunneling in Fe8 with excited nuclei<\/a>, Phys. Rev. B., 82, (2010) 014419.<\/li>\n<\/ul>\n
Abstract:
\nWe investigate the effect of dynamic nuclear-spin fluctuation on quantum tunneling of the magnetization (QTM) in the molecular magnet Fe8<\/sub> by increasing the nuclei temperature using radio frequency (rf) pulses before the tunneling measurements. Independently we show that the nuclear-spin-spin relaxation time T2<\/sub> has strong temperature dependence. Hence, in principle, the rf pulses should modify the nuclear-spin dynamic. Due to very long spin-lattice relaxation time, the rf pulses do not change the electrons spin temperature. Nevertheless, we found no effect of the nuclear-spin temperature on the tunneling probability. This suggests that in our experimental conditions only the hyperfine-field strength is relevant for QTM. We demonstrate theoretically how this can occur.<\/p>\n- \n
- O.Shafir and A.Keren, Electromagnetic radiation emanating from the molecular nanomagnet Fe8<\/a>, Phys. Rev. B., 79, (2009) 180404(R).<\/li>\n<\/ul>\n
Abstract:
\nPhotons emitted by transition between the discrete levels of single molecular magnets might obey the elementary condition for Dicke’s super-radiance. We investigate this possibility in the Fe8<\/sub> molecule where magnetization jumps are known to occur at discrete magnetic-field values. We found energy bursts each time the molecule undergoes a magnetization jump, confirming their quantum nature. A series of tests indicated that photons carry out the energy and that indeed these photons obey the elementary conditions for super-radiance.<\/p>\n- \n
- A.Keren, O.Shafir, E.Shimshoni, V.Marvaud, A.Bachschmidt and J.Long, Experimental Estimates of Dephasing Time in Molecular Magnets<\/a>, Phys. Rev. Lett., 98, (2007) 257204.<\/li>\n<\/ul>\n
Abstract:
\nMuon spin relaxation measurements in isotropic molecular magnets (MM) with a spin value S<\/i> ranging from 7\/2 to 27\/2 are used to determine the magnitude and origin of dephasing time \u03c4\u03d5<\/sub><\/i> of molecular magnets. It is found that \u03c4<\/i>\u03d5<\/i><\/sub> ~ 10 nsec with no S<\/i> or ligand dependence. This indicates a nuclear origin for the stochastic field. Since \u03c4<\/i>\u03d5<\/i><\/sub> is a property of the environment, we argue that it is a number common to similar types of MM. Therefore, \u03c4<\/i>\u03d5<\/i><\/sub> is shorter than the Zener and tunneling times of anisotropic MM such as Fe8<\/sub> or Mn4<\/sub> for standard laboratory sweep rates. Our findings call for a stochastic Landau-Zener theory in this particular case.<\/p>\n\n- \n
- O.Shafir, A.Keren, S.Maegawa, M.Ueda, A.Amato, C.Baines, Demonstrating multibit magnetic memory in the Fe8 high-spin molecule by muon spin rotation<\/a>, Phys. Rev. B, 72, (2005) 092410.<\/li>\n<\/ul>\n
Abstract:
\nWe develop a method to detect the quantum nature of high-spin molecules using muon spin rotation and a three-step field cycle ending always with the same field. We use this method to demonstrate that the Fe8<\/sub> molecule can remember six (possibly eight) different histories (bits). A wide range of fields can be used to write a particular bit, and the information is stored in discrete states. Therefore, Fe8<\/sub> can be used as a model compound for multibit magnetic memory. Our experiment also paves the way for magnetic quantum tunneling detection in films.<\/p>\n\n- \n
- Z. Salman, A Keren, S. Megeawa, M. Ueda, O. Shafir, B. Barbara, C. Baines, Probing magnetic quantum tunneling in Fe8<\/sub> with muons<\/a>, Physica B 326, (2003) 480-483.<\/li>\n<\/ul>\n
Abstract:
\nWe present a muSR<\/span> study of the Fe8<\/sub> molecules from which an evidence of quantum tunneling of the magnetization (QTM) can be seen, in the form of drastic changes in the local field experience by the muon<\/span>.<\/span><\/p>\n<\/div>\n\n- \n
- Z. Salman, A Keren, P. Mendels, V. Marvaud, A. Scuiller, M. Verdaguer, J. S. Lord, and C. Baines, Dynamics at T–>0 in the half-integer isotropic high spin molecules<\/a>, Phys. Rev. B 65,\u00a0 (2002) 132403.<\/li>\n<\/ul>\n
Abstract:
\nWe investigate the dynamical spin-spin auto-correlation function of the isotropic high spin molecules CrCu6<\/sub>(S=9\/2),\u00a0 CrNi6<\/sub><\/span> (S=15\/2) and CrMn6<\/sub> (S=27\/2), using magnetization, muSR<\/span> and NMR measurements. We find that the field autocorrelation time tau<\/i><\/span> of the molecule’s spin at zero and low fields is nearly temperature independent as T –> 50 mK<\/span><\/span>, indicating that it is induced by a quantum process. The high temperatures tau<\/i><\/span> is very different between the molecules. Surprisingly, it is identical (~10 nsec<\/span>) at base temperature.<\/p>\n<\/div>\n
- Z. Salman, A Keren, P. Mendels, V. Marvaud, A. Scuiller, M. Verdaguer, J. S. Lord, and C. Baines, Dynamics at T–>0 in the half-integer isotropic high spin molecules<\/a>, Phys. Rev. B 65,\u00a0 (2002) 132403.<\/li>\n<\/ul>\n
- Z. Salman, A Keren, S. Megeawa, M. Ueda, O. Shafir, B. Barbara, C. Baines, Probing magnetic quantum tunneling in Fe8<\/sub> with muons<\/a>, Physica B 326, (2003) 480-483.<\/li>\n<\/ul>\n
- O.Shafir, A.Keren, S.Maegawa, M.Ueda, A.Amato, C.Baines, Demonstrating multibit magnetic memory in the Fe8 high-spin molecule by muon spin rotation<\/a>, Phys. Rev. B, 72, (2005) 092410.<\/li>\n<\/ul>\n
- A.Keren, O.Shafir, E.Shimshoni, V.Marvaud, A.Bachschmidt and J.Long, Experimental Estimates of Dephasing Time in Molecular Magnets<\/a>, Phys. Rev. Lett., 98, (2007) 257204.<\/li>\n<\/ul>\n
- O.Shafir and A.Keren, Electromagnetic radiation emanating from the molecular nanomagnet Fe8<\/a>, Phys. Rev. B., 79, (2009) 180404(R).<\/li>\n<\/ul>\n
- O.Shafir, A.Keren, S.Maegawa, M.Ueda, and E.Shimshoni, Magnetic quantum tunneling in Fe8 with excited nuclei<\/a>, Phys. Rev. B., 82, (2010) 014419.<\/li>\n<\/ul>\n
- T.Leviant, S.Hanany, Y.Myasoedov, and A.Keren, Testing the radiation emanating from the molecular nanomagnet Fe8<\/sub> during magnetization reversals<\/a>, Phys. Rev. B., 90, (2014) 054420.<\/li>\n<\/ul>\n