Magnetically tunable rf wave absorption in polycrystalline La0.67Ba0.33MnO3

Abstract

We investigated temperature and magnetic field dependent radio-frequency electromagnetic absorption in La0.67Ba0.33MnO3 by monitoring changes in resonance frequency (fr) and current (I) through a LC resonant circuit powered by an integrated chip oscillator. The ferromagnetic to paramagnetic transition at TC in zero magnetic field is accompanied by an abrupt increase in fr and I and they are tunable by small external magnetic field. We observed fractional changes as much as 46% in Δfr/fr and 23% in ΔI/I around TC under μ0H=0.1 T that can be exploited for low-magnetic field sensors and other applications.

Transverse susceptibility as a probe of the magnetocrystalline anisotropy-driven phase transition inPr0.5Sr0.5CoOHuls1, Bingham2, Phan3 et al. 2011Phys. Rev. B310200View full textAdd to dashboardCite

“…This technique has been used with great success to examine the anisotropic magnetic properties of a variety of systems from multilayered thin films [34] to single crystals [35] and nanoparticles [36,37]. However it also lends itself particularly well to the rich physics involved in complex oxide systems to examine the unusual magnetic behavior often seen in manganites [28,32,35,39] and, as we show here, cobaltites.…”

Detection of structural and magnetic transitions in La0.67Ba0.23Ca0.1MnO3 using the rf resonance technique

“…For rf power absorption study, the inductance coil loaded with sample was mounted in a specially designed sample holder wired with high frequency coaxial cables and the magnetic field was applied along the coil axis. Temperature and magnetic field dependent radio-frequency (rf) electromagnetic absorption has been investigated using a home built LC resonant circuit powered by an integrated chip oscillator (ICO) [12,13]. shows a small peak at T¼300 K, which is followed by a broad maximum around 225 K. The peak at T¼300 K coincides with the onset of the ferromagnetic transition at T¼T C as determined by the ac susceptibility and the broad peak around 225 K is of non-magnetic origin and is possibly caused by the scattering of charges by grain boundaries or other inhomogeneities such as oxygen vacancies [14].…”

“…The LC-tank resonance circuit biased by tunnel-diode was exploited to study the London penetration depth in superconductors [8], to detect the magnetic transition and to analyze the critical exponents in some magnetic materials [9,10], and also to study the electrical conductivity without making contact to the sample [11]. Very recently, we have used a series LC resonance circuit powered by a commercially available integrated chip (IC 74LS04-TTL bipolar Hex inverter) to study the electrodynamics of La 0.67 Ba 0.33 MnO 3 compound [12], and we observed fractional changes as much as 46% in resonance frequency shift (Df r /f r ) and 23% in power absorption (DP/P) around T C under H¼1 kG. These results suggest that rf absorption can be used to probe the magnetic transition and to make the rf devices using manganites for magnetic field sensing applications.…”

Sample thickness dependence of giant magnetoimpedance under low fields for La0.67Sr0.33Mn0.98Co0.02O3 manganites

“…The spin-polarized tunneling through the interfaces of grains or spin-dependent scattering at grain boundaries has been suggested to be responsible for the LFMR [5,6]. In addition to CMR and LFMR, La 1-x A x MnO 3 based manganites also exhibit colossal magnetoabsorption in the microwave highfrequencies (∼GHz) [7,8] and giant magnetoimpedance in radio frequencies (∼MHz) [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. For metallic manganites below Curie temperature, a high frequency current passes the sample mainly through its surface region characterized by the penetration depth ı = 2 / 0 t ω ( is the resistivity, 0 vacuum permeability, t transverse permeability of material, ω the angular frequency of current) and a strong magnetoimpedance could occur, which originates from the variation of t induced by the applied DC magnetic field, via the change of penetration depth ı.…”