title: Novel dielectric anomalies due to spin-chains above and below Néel temperature in Ca3Co2O6.
abstract: We bring out novel dielectric behavior of a spin-chain compound, Ca3Co2O6, undergoing Néel order at (TN = ) 24 K. It is found that the virgin curve in the plot of isothermal dielectric constant (ε') versus magnetic-field lies outside the 'butterfly-shaped' envelope curve well below TN (e.g., 2.6 K), with a signature of a partial arrest of the high-field magnetoelectric (ME) phase in zero-field after travelling through magnetic-field-induced magnetic transitions. This behavior is in contrast to that observed in the isothermal magnetization data. Thus, this work brings out a novel case for 'phase-coexistence phenomenon' due to ME coupling. Another strange finding is that there is a weak, but a broad, peak in ε' around 85-115 K well above TN, attributable to incipient spin-chain magnetic ordering. This finding should inspire further work to study ME coupling on artificial assemblies of magnetic chains, also keeping in mind miniaturization required for possible applications.
authors.affiliation: Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai - 400005, India.
authors.forename: Tathamay
authors.initials: T
authors.lastname: Basu
authors.forename: Kartik K
authors.initials: KK
authors.lastname: Iyer
authors.forename: Kiran
authors.initials: K
authors.lastname: Singh
authors.forename: E V
authors.initials: EV
authors.lastname: Sampathkumaran