Abstract
We report the results of a systematic investigation of the phase diagram of the iron-based superconductor Ba 1-xK xFe 2As 2 from x = 0 to x = 1.0 using high-resolution neutron and x-ray diffraction and magnetization measurements. The polycrystalline samples were prepared with an estimated compositional variation of Δx 0.01, allowing a more precise estimate of the phase boundaries than reported so far. At room temperature, Ba 1-xK xFe 2As 2 crystallizes in a tetragonal structure with the space group symmetry of I4/mmm, but at low doping, the samples undergo a coincident first-order structural and magnetic phase transition to an orthorhombic (O) structure with the space group Fmmm and a striped antiferromagnet (AF) with the space group F cmm′m′. The transition temperature falls from a maximum of 139 K in the undoped compound to 0 K at x = 0.252, with a critical exponent as a function of doping of 0.25(2) and 0.12(1) for the structural and magnetic order parameters, respectively. The onset of superconductivity occurs at a critical concentration of x = 0.130(3), and the superconducting transition temperature grows linearly with x until it crosses the AF/O phase boundary. Below this concentration, there is microscopic phase coexistence of the AF/O and superconducting order parameters, although a slight suppression of the AF/O order is evidence that the phases are competing. At higher doping, superconductivity has a maximum T c of 38 K at x = 0.4 that falls to 3 K at x = 1.0. We discuss reasons for the suppression of the spin density wave order and the electron-hole asymmetry in the phase diagram.
| Original language | English |
|---|---|
| Article number | 184507 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 85 |
| Issue number | 18 |
| DOIs | |
| Publication status | Published - May 7 2012 |
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ASJC Scopus subject areas
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials
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Phase diagram of Ba 1-xK xFe 2As 2 . / Avci, S.; Chmaissem, O.; Chung, D. Y.; Rosenkranz, S.; Goremychkin, E. A.; Castellan, J. P.; Todorov, I. S.; Schlueter, J. A.; Claus, H.; Daoud-Aladine, A.; Khalyavin, D. D.; Kanatzidis, Mercouri G; Osborn, R.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 85, No. 18, 184507, 07.05.2012.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Phase diagram of Ba 1-xK xFe 2As 2
AU - Avci, S.
AU - Chmaissem, O.
AU - Chung, D. Y.
AU - Rosenkranz, S.
AU - Goremychkin, E. A.
AU - Castellan, J. P.
AU - Todorov, I. S.
AU - Schlueter, J. A.
AU - Claus, H.
AU - Daoud-Aladine, A.
AU - Khalyavin, D. D.
AU - Kanatzidis, Mercouri G
AU - Osborn, R.
PY - 2012/5/7
Y1 - 2012/5/7
N2 - We report the results of a systematic investigation of the phase diagram of the iron-based superconductor Ba 1-xK xFe 2As 2 from x = 0 to x = 1.0 using high-resolution neutron and x-ray diffraction and magnetization measurements. The polycrystalline samples were prepared with an estimated compositional variation of Δx 0.01, allowing a more precise estimate of the phase boundaries than reported so far. At room temperature, Ba 1-xK xFe 2As 2 crystallizes in a tetragonal structure with the space group symmetry of I4/mmm, but at low doping, the samples undergo a coincident first-order structural and magnetic phase transition to an orthorhombic (O) structure with the space group Fmmm and a striped antiferromagnet (AF) with the space group F cmm′m′. The transition temperature falls from a maximum of 139 K in the undoped compound to 0 K at x = 0.252, with a critical exponent as a function of doping of 0.25(2) and 0.12(1) for the structural and magnetic order parameters, respectively. The onset of superconductivity occurs at a critical concentration of x = 0.130(3), and the superconducting transition temperature grows linearly with x until it crosses the AF/O phase boundary. Below this concentration, there is microscopic phase coexistence of the AF/O and superconducting order parameters, although a slight suppression of the AF/O order is evidence that the phases are competing. At higher doping, superconductivity has a maximum T c of 38 K at x = 0.4 that falls to 3 K at x = 1.0. We discuss reasons for the suppression of the spin density wave order and the electron-hole asymmetry in the phase diagram.
AB - We report the results of a systematic investigation of the phase diagram of the iron-based superconductor Ba 1-xK xFe 2As 2 from x = 0 to x = 1.0 using high-resolution neutron and x-ray diffraction and magnetization measurements. The polycrystalline samples were prepared with an estimated compositional variation of Δx 0.01, allowing a more precise estimate of the phase boundaries than reported so far. At room temperature, Ba 1-xK xFe 2As 2 crystallizes in a tetragonal structure with the space group symmetry of I4/mmm, but at low doping, the samples undergo a coincident first-order structural and magnetic phase transition to an orthorhombic (O) structure with the space group Fmmm and a striped antiferromagnet (AF) with the space group F cmm′m′. The transition temperature falls from a maximum of 139 K in the undoped compound to 0 K at x = 0.252, with a critical exponent as a function of doping of 0.25(2) and 0.12(1) for the structural and magnetic order parameters, respectively. The onset of superconductivity occurs at a critical concentration of x = 0.130(3), and the superconducting transition temperature grows linearly with x until it crosses the AF/O phase boundary. Below this concentration, there is microscopic phase coexistence of the AF/O and superconducting order parameters, although a slight suppression of the AF/O order is evidence that the phases are competing. At higher doping, superconductivity has a maximum T c of 38 K at x = 0.4 that falls to 3 K at x = 1.0. We discuss reasons for the suppression of the spin density wave order and the electron-hole asymmetry in the phase diagram.
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U2 - 10.1103/PhysRevB.85.184507
DO - 10.1103/PhysRevB.85.184507
M3 - Article
VL - 85
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 18
M1 - 184507
ER -