Effects of Zn substitution on the superconductivity and pseudogap inHgBa2CuO4+δwith various doping levels

Crystal Growth and Characterization of the Model High‐Temperature Superconductor HgBa2CuO4+δ

“…Our annealing tests show that the optimal annealing conditions depend strongly on crystal size and shape. The T c onset can be as high as 97 K (very close to the maximum value of T c = 98 K reported for powder samples [12] ) and the transition width is typically less than 5 K for small crystals (∼ 10 mg) and 8 K for large crystals. Since impurity effects tend to lower and broaden the transition, [2] this high value of T c and the reasonably sharp transition suggest that large parts of our crystals are of the highest quality attained to date.…”

“…The extracted room-temperature lattice parameters for the as-grown crystals were a = 3.886 Å and c = 9.517 Å, in agreement with previously published results. [11,12,14] A known feature of Hg1201 is the Hg off-stoichiometry, with a Hg deficiency that has been found to range from 8 % to 20 %. [14,[25][26][27] To determine the stoichiometry of a typical large crystal, we used inductively coupled plasma mass spectroscopy (ICP-MS).…”

“…A straightforward method is to simply mix BaO or BaO 2 with CuO. [11,12] Unfortunately, at room temperature, barium oxide and peroxide easily react with water or CO 2 , forming Ba(OH) 2 or BaCO 3 . For this reason, commercially available BaO is contaminated, and consequently not suitable for precursor preparation.…”

“…Conventional encapsulation also allow crystal growth. [11][12][13][14][15][16][17][18][19] Based on this method, several improvements have been developed, including the use of a three-zone furnace to control the partial pressure of mercury; all these efforts resulted in either powder samples or crystals sized smaller than one cubic millimeter. [18,[20][21][22][23] In contrast to the sophisticated methods mentioned above, we adopted a conventional encapsulation approach.…”

Phonon softening in HgBa 2 CuO 4+ δ observed by inelastic X‐ray scattering

“…The crystal structure is tetragonal, forming a completely square and flat CuO 2 plane. Moreover, the absence of the 1/8-anomaly suggests that the static stripes play a small role in Hg1201 [4]. Hg1201 is also interesting because the structure is similar to LSCO, while T c (∼98 K) is similar to YBCO, and the member of this (Hg based) family of the high-T c cuprates have the highest T c to date (T c ∼135 K).…”